I'm Luke Hague a criminalist and
forensic Firearms examiner involved in
the examination of such evidence in this
initial tape we're going to look at some
basic information concerning Firearms
ammunition its construction bullet
design propellants Firearms design how
the cartridge and the firearm go
together
how marks are created on cartridges and
bullets of course I'll discuss briefly
how the identifications are made but
more importantly this is background
information that's useful to a wide
variety of audiences a reading of any
police report or trial transcript is
frequently revealed that investigators
and lawyers on both sides don't really
fully understand or exploit this
valuable evidence so there are a number
of audiences out there I intend to
address first of all the police officers
who first arrive on the scene of a
shooting incident
the detectives that will follow up in
that investigation and evaluate and
gather evidence and submit it to the
laboratory some agencies have special
shooting response teams that are
involved in in the investigation of
officer-involved shootings criminalists
and crime Laboratories that work in
other units of the laboratory such as
trace evidence serology that need a
better understanding of what the
Firearms examiner does so the two of
them can combine their efforts in the
effective solution of a case Prosecuting
attorneys of course who represent the
state in crimes involving criminal use
of firearms really in three respects
first of all they must interact with the
police investigators and the laboratory
in formulating the appropriate protocol
for the analysis of the evidence
secondly they have to prepare for trial
they have to understand what those
findings are and how they relate to the
charge and lastly obviously actual trial
presentation of technical Witnesses
investigators and preparation for
redirect examination or Rehabilitation
of their own experts that leads to
defense attorneys who must understand
what tests were carried out by the
laboratory what the purpose was what the
findings mean if the proper tests were
indeed carried out and finally what
could or should may still need to be
done
civil attorneys both plaintiff and
defense in three areas products
liability or a firearm or ammunition is
alleged to be defective accidental
shootings hunting accidents for example
and finally again officer-involved
shootings where agencies typically find
themselves being sued as a consequence
of such a incident last group would be
forensic Pathologists and or emergency
room surgeons who are involved in
recovering not only projectiles but
oftentimes describing the injury
locating trace evidence associated with
such injuries powder particles for
example and ultimately turning those
matters over to the investigators
in this tape we're going to look at
ammunition construction bullet design
propellants the design of the Firearms
how the ammunition fits in those guns
and receives marks from it
identification of course and finally a
little bit about shotgun evidence a
whole separate category and that leads
us to the two types of cartridges that
we'll be involved with they can fit in
one of two categories metallic
cartridges which have a bullet of some
kind
a brass or metallic cartridge case with
the propellant and some sort of primer
something to ignite this propellant
charge and drive the bullet out the bore
of the gun
a very different type of ammunition that
is on occasion involved in crimes or
shotguns and a shotgun shell is a very
complicated Affair behaves very
differently than bulleted ammunition as
we'll see so we can put things in those
two broad categories in the metallic
cartridges we have again a subdivision
22 rim fire being the most common
cartridge that crime Laboratories have
encountered over the years and probably
accounts for more deaths than any other
cartridge
and yet as thought of as not a
particularly powerful round this
particular illustration is just a small
sampling of various brands of 22 Rimfire
cartridges I'll describe more about how
these are constructed in a moment but
before that there are three loadings
commonly available in 22 Rimfire the 22
short
which has a as the name would suggest a
short cartridge case and a small
nominally 27 29 grain lead bullet
sometimes with a copper veneer or wash
over it a plating
the next loading is the 22 long now this
has a longer cartridge case but uses the
same bullet that the 22 short does so if
we were to find bullets from of this
type at a crime scene without the
cartridge case they could be from either
22 short or 22 long since they are the
very same except for the length of the
cartridge case
the next four examples in this
illustration are three different
companies versions or brands or loadings
of 22 long rifle here if you look at the
illustration you'll see that the
cartridge case is the same length as the
long but the bullet is bigger in fact
visually it's longer and indeed in a 22
long rifle cartridge those bullets will
typically weigh anomaly 40 grains grain
being the unit of weight used in
American ammunition
for a total of seven thousand grains in
a pound if you're trying to get some kin
or sense for what that amounts to there
are some other features in these four
bullets I draw your attention to notice
that the first two
are copper colored that's not really a
jacket that's simply a thin plating
that's been deposited on an otherwise
lead bullet we can also see some
knurling some indentations on each one
of these bullets one on the one on the
left happens to be made by federal
one of the big four in ammunition
manufacturer in the United States the
next cartridge happens to be one made by
Winchester and it has three of these
little knurled grooves we'll talk a lot
more about those and other types of
ammunition but to start using terms that
we should become familiar with that's
called a cantalure
the next bullet also made by Winchester
is essentially indistinguishable from
the previous bullet except that it lacks
the copper plating
in fact Winchester has a patented name
for that copper plating process it's
called lubaloy
so here's a product they've prepared
with and without the lubeloy or the
copper plating the last bullet also a 22
long rifle the cartridge case is the
same length as the previous three it
also has
can alluring on it we can see two
cantalers on that particular bullet it
also has a copper plating or finish but
has a very different shape and that
particular type or shape is called a
truncated cone we can see the conical
shape that if it continued it'd lead to
a point it's simply been truncated
now each one of these projectiles if we
were to look at them from a top view may
also be Hollow pointed that is they
could the manufacturer could form a
hollow cavity in the nose of this
projectile to improve its expansion
characteristics in game animals or
tissue stimulants
here's six more 22 long rifle cartridges
again with a little more variety to give
you a feeling of yet another feature
called the head stamp that is the
written information on the base of the
cartridge that's useful in deciding what
brand of ammunition is involved in a
particular incident
I've also added another somewhat unusual
22 long rifle cartridge at least it
qualifies as a 22 long rifle by the
industry called a stinger made by CCI or
omark Industries and here's their unique
head stamp a letter C on the base of
this nickel plated cartridge different
than the other five we're looking at it
too has a copper plated bullet this is
not a jacketed bullet it's simply a lead
bullet with a thin copper plating
but the unique thing about this
particular round is the lack of any
cantal lures and at this time this is
1991. that's the only 22 round I'm aware
of made in the United States at least
that lacks any cantaluring and that
could be useful in deciding even from a
bullet fragment which of these six
candidates or examples we're dealing
with
the next one we've seen previously
that's the Winchester with three neural
cannellers the lubaloy plating and
although it's upside down we can see a
head stamp that reads Super X a very
popular head stamp that if you've shot
22s and picked up cartridges you've
probably seen a bunch of these
here's that look-alike with the lead
bullet without the plating that's
presently being loaded by Winchester in
a product called the 22 Wildcat hence
the stylized W on their cartridge here's
our federal cartridge we saw earlier
with an F for a head stamp the next one
we haven't seen yet also a very popular
cartridge Remington's entry into the 22
long rifle product line and this is
their previous head stamp a letter U
that Remington is historically used for
many many years until about several
years ago when they switched to an REM a
little easier to understand the origin
with that particular head stamp the U
came historically from the Union
metallic cartridge company of the Civil
War era on into this Century but look at
the Remington bullet for a moment it
also has a brassy finish instead of a
copper colored finish and that's useful
information because it sets the
Remington bullets apart from all the
other manufacturers if for example we
had a bullet that was badly damaged we
had several Shooters we saw all that
some of the cartridge casings were
Federal from one person's gun some of
the cartridge casings were Remington
that we could identify with another
individual's gun but basically all we
had was a splattered bullet or a heavily
damaged bullet unsuitable for
identification but if we could see that
brassy finish if our population is just
those two if the universe of available
guns and ammunition in that case are
those two choices
then we can say by exclusion it can't be
the federal or the Winchester because
this bullet fragment has this Remington
finish on it
so that's part of part of my thesis in
this presentation there are many things
we can do with Firearms evidence when we
can't make an identification when we
don't have the ability to identify the
responsible gun because a terminal
ballistic damage other other reasons
here's the one I showed you earlier the
truncated cone bullet and the Remington
head stamp the new style head stamp
here's a little more expanded view of
some head stamps still in 22 rim fire
and again I'll add a little information
with each description
here's CCIS that I described earlier
they recently I reiterate this is 91
they've just gone to a slightly reduced
C still the same style here's our Super
X right side up
the U for Remington the Contemporary REM
here's a very old Winchester round with
the H on it
this is a European round a letter D with
a z in the middle of it again another
round from Germany with a shield and a
letter r this CI headstamp you're
looking at is a Mexican cartridge it's
being imported by technical Industries
near Mexico City the Z which is probably
very vague is also an import
and several other Imports in the lower
row that instead of having letters or
names simply have some sort of symbol
PMC ammunition also being imported and
soon to be made in the United States
simply has this double triangle
I've added three others here that have
firing pin Impressions to start
orienting you to why they're called a
rim fire cartridge the priming mixture
the material that makes the propellant
burn
in a Rimfire cartridge is located out in
this rim and it is literally pinched by
the firing pin of the gun at the moment
of impact of the firing pin that
detonates the priming mixture ignites
the propellant and of course the bullet
then's driven out the barrel but in a
fired Rimfire cartridge somewhere around
this Rim will be located a firing pin
impression and it can be rectangular it
can be round it can be hemispherical in
fact in this last example the cartridge
with the f on it which we now should
realize is made by federal it's
triangular that particular one happens
to have been fired in one of my own
reference guns of marlin
the other type of cartridge I mentioned
is a general categorization Center fire
cartridges are ignited in a very
different way as the name suggests
Center fire they have a primer this is a
fixture a little cup that has an
explosive mixture in it a literally
shock sensitive explosive mixture
that when the firing pin crushes that
material in the primer cup a jet of
flame and Sparks are driven through a
small opening called a flash hole into
the propellant charge in this particular
cutaway we can see the cartridge case
filled with smokeless powder in this
case it's a form called ball powder
all the way up to the base of the bullet
which also has been cross-sectioned and
in this particular example we have a
copper jacketed bullet this is not a
plating or a thin veneer but rather an
actual formed copper jacket or Cup in
which the Lead Core has been inserted
here's some representative examples
going from pistol cartridges on up to a
rifle cartridge that are all Center fire
on the left is a European nine
millimeter Parabellum sometimes called
nine millimeter Luger the bullet is a
full metal jacketed bullet with a nickel
plating on it to give it that silvery
color the next cartridge is another nine
millimeter cartridge this one happens to
be made in Israel and the black tip is
an indicator that's it's meant strictly
for a particular type of firearm namely
the uzi submachine gun
and the reason is the pressures that
this cartridge develops are greater than
those that handguns are designed to
handle backing up to the previous
cartridge one might see a slight color
difference a Browner color to that
cartridge that cartridge is made of
steel with a epoxy or plastic-like
coating on it that brings up another
Point cartridges the metal fixture in
which the bullet is seated and the
propellant is held
commonly are made of brass in the United
States but they can also be made of
steel and that's very popular in Europe
in the communist countries because of
the scarcity of brass and the expense
there are also a few one particular in
the United States that's even made of
aluminum and we'll come to that the next
cartridge has a brass case but it's been
nickel plated and it has a lead bullet
in it which has been coated with nylon
this is Federal's nyclad so there would
be an absolutely unique item at this
time a bullet that's completely plated
or covered with a nylon plating or I'm
sorry a nylon coating
and that for interest perhaps is to
reduce lead levels in indoor shooting
ranges it also makes the identification
process rather difficult
the next bullet also has some interest
because it has shown up in two shooting
cases one in Nevada One in California
and yet at the same time is a very rare
and scarce item to some observers out
there it may look familiar but that's
only illusionary this 38 Special round
brass cartridge case with what appears
to be a round nose copper jacketed
bullet it's a common round or appears to
be a common round that our military
issued to Air Force pilots
in fact this particular bullet was a
research project and it's actually a
steel bullet well one might ask well how
can a steel bullet look copper colored
what they've done in this particular
instance is simply put a copper plating
on the projectile
and I have one of these rounds here one
from one of the actual cases that if you
were to pick it up or find this Bullet
at a scene you might believe you're
looking at a copper jacketed bullet
but in fact as this magnet will reveal
we've got a steel bullet now that may
seem esoteric but that can lead to the
solution or resolution of an issue in a
case for example television is ruining
ruining us all as far as what jurors
expect to hear Firearms do when they
hear testimony in the courtroom even
citizens anticipating what they should
see when guns are fired
we all now know from watching television
for the last two years the bullets make
sparks when they hit walls and sidewalks
that's not true
brass and copper lead don't make sparks
but that bullet that I just showed you
being steel if it were to hit the
sidewalk indeed we might see what's
depicted commonly on television
the last cartridge in this particular
illustration is the Contemporary Soviet
AK-74 round it's very similar to our
5.56 millimeter cartridge insofar as
what it's intended for uh it's caliber
its velocity but I've put it up here for
for several reasons we can see that with
rifle bullets they're quite long the
typical characteristic of a pistol
bullet is big and short and usually with
a straight cartridge case with no
shoulder in it typical rifle cartridges
have a bottleneck or a shoulder in them
and the bullets they shoot are typically
very long as compared to their diameter
and this bullet is especially so it also
has a red lacquer sealing the area
between the bullet and the mouth of the
cartridge case
this lacquer can survive the actual
discharge process even though it's on
the bearing surface of the bullet and
that again can be useful trace evidence
as we'll see in some other cases later
here's a lineup of
a number of rifle cartridges now that
you've got the idea that rifle
cartridges typically some exceptions are
a bottlenecked cartridge with a long
bullet
these are quite colorful in that they've
also got painted tips some orange some
red some blue depending on the country
of origin these are indicators for
whether the projectile the bullet is
either armor piercing incendiary or
Tracer with or without a delay
not many shootings or crimes occur with
this ammunition but nonetheless they do
on occasion occur in fact there's a very
well done Case by a criminalist in
California where
this orange material you can see on the
last example on the right was left in
the feed ramp of a hunter's rifle where
a forest fire was created by a tracer
bullet and this particular individual
denied ever firing Tracer ammunition in
his rifle he volunteered the gun to the
game warden and the laboratory in
connection with an officer who
understood something about this kind of
ammunition even though the bullet was
burned and discolored when they found it
at the point of origin submitted that
rifle to the laboratory to be examined
and traces of this color and this type
of paint were located in the feed ramp
in the mechanism again something we'll
talk more about in a moment of the rifle
taken from the hunter confronted with
that sort of evidence the man confessed
to his involvement in shooting these
rounds into a wooded area so my thesis
again understanding something about
ammunition and the relationships the
exchanges that can take place between
ammunition and gun or impact or Target
becomes very important the only pistol
round have in this picture is on the far
left it's a little 25 automatic but it
too although may be difficult to see has
this colored lacquer between the case
mouth and the bullet that can be again
left in the gun it can survive and some
of it will still be on the bullet after
discharge
another product line that of
Winchester's that's achieved some
popularity of particularly in the law
enforcement Community this round or this
line of ammunition is called Silver Tip
some not all of these have a very unique
Construction in that the jacket that's
the portion that's around the Lead Core
of the bullet is composed of aluminum
now up to this point I've talked to you
about lead bullets lead bullets with a
thin copper plating lead cores inside of
copper jackets steel bullets steel
bullets with copper plating now we've
got a bullet that again is constructed
with a Lead Core
but it has an aluminum jacket around it
for example the 380 automatic and 32
automatic entries the 45 automatic
entries into this particular product
line have aluminum instead of
copper jackets the ones that look quite
shiny in this illustration for example
nine millimeter is actually a copper
jacket with a nickel plating on it well
the point of all this is several four
let's imagine we have a person deceased
from a gunshot injury the medical
examiner pulls out what appears to be a
lead bullet
and x-rays reveal one radio opaque
object close inspection of that lead
bullet
reveals it's simply a core
and I'll illustrate or give you an
example of one of those if I can take
just a moment I have here both a fired
and unfired
380 automatic
Winchester Silvertip projectile here's
the unfired projectile
and here's a recovered projectile from a
decedent in two parts the separated
aluminum jacket
and the Lead Core that to the Casual
Observer and that may even be a medical
examiner or a detective looks like a
fired bullet some of the rifling
impressions have actually printed
through this very thin aluminum jacket
into the core but they're not striated
they're simply faint smooth vestiges of
the rifling Engravings and that's the
tip-off so it would behoove
investigators to have the laboratory
give them something like this so they're
familiar with this problem and here's
the problem
this is the entity the item but the
identification of the responsible gun
will be made on
it doesn't show up on x-rays
it may well still be in the body so if
you're the detective at the autopsy
scene the medical examiner pulls out a
core with or without the knowledge that
you may be dealing with a silver tip the
likelihood is this little item is still
down in the body somewhere and they're
going to have to go back and look for it
an exhumation or looking through
cremation remains is a real pain and
these indeed may go through the screen
and I have done this gone through
cremation remains looking for things
like this because the initial
investigators fail to recognize the
separation of a jacket
a bullet jacket
this particular illustration is from
Remington and it's useful because it
shows us something more about bullet
design
we've got a number of types of
projectiles here some of which we've
talked about here's a copper jacketed
bullet
with an exposed Lead Core here's our
cantler that we've talked about
let's look at that one for a moment
notice the scalloping of the jacket as
it meets the lead right now that's a
patented process of Remington and
protected by them
how would that be useful once again all
bullets don't come out Pristine from
shootings they can hit the brick walls
the sides of police cars and even break
up on bone inside of bodies if we simply
had this portion a piece of that
scalloped jacket we'd at least be able
to say we're dealing with a Remington
bullet and again in many shootings our
universe of possible guns and ammunition
maybe just two or three Shooters one
officer armed with Remington ammunition
from agency a and officer B
with Winchester Silvertip and if that's
the question who scored this hit or who
made this shot we could resolve it just
on what are called class characteristics
the manufacturing features of the bullet
look at another example Remington also
makes bullets with a just a sharp
boundary between the exposed Lead Core
in this example and the copper jacket
notice that the cantalore on that bullet
against the previous one is at a very
different position so here's another
opportunity let's say we otherwise have
bullets that are the same caliber same
basic weight but the position of the
cantaler can be useful in determining
what that original bullet weight was the
manufacturer has put that there with
mathematical Precision for a purpose and
it's partly product identification
the next bullet is commonly associated
with semi-automatics and submachine guns
full metal jacketed bullets just like
the movie Full Metal Jacket here is one
the copper jacket extends all the way
around the core usually LED of the
bullet that means that the lead had to
be inserted from the back end
let's go back to the previous bullet
think about it a minute if you've got a
copper jacket and you're going to put a
Lead Core in it you're going to have it
exposed at the nose then the lead has to
go in from the front end
and we can see those features even in
badly damaged bullets that they have an
open base in other words the lead was
introduced from the base of the bullet I
immediately know when I see that that I
was dealing with a full metal jacketed
bullet even though it may be badly
damaged conversely if I have an enclosed
base and can find some termination point
of a jacket and I was dealing with
either a hollow point or a soft point
the next bullet down popular in target
shooting it's called a wad gutter
because it cuts a little wad of paper
out of the Target also Cuts nice round
holes in people or clothing and this one
has three cantal lures and they're of
different sizes again that would
undoubtedly be unique to Remington's wad
cutter as opposed to Winchester Federal
and other companies that make wad cutter
bullets the top of the chart on the
other side we have a semi wad cutter
it's nearly flattened off but it's got
somewhat of a conical nose which has
been truncated hence semi-wad cutter the
next round is fairly uncommon now a
metal point where they put a copper
cup or point over the nose of the bullet
and the rest is lead
the next one has what's called a gas
check on it this is simply a little
copper cup that protects the base of the
bullet during firing and it protects it
from the erosion of lead and the leading
of the bore of the gun a problem that
reduces accuracy these little copper gas
checks sometimes will fall away or break
away
when a bullet impacts something or goes
into a body occasionally they'll even
separate in flight but that's usually a
problem with putting the bullet together
the important thing is they tell me
again something about the kind of bullet
I'm dealing with they also have rifling
Engravings on them because those gas
checks are in the bearing area the
bearing surface of the bullet they
contacted the riflings of the gun and
the bottom one's probably at least
traditionally the most common pistol
bullet we encounter just a normal lead
round nose bullet popularly used for
example in 38 special and 158 grain
loading police officers for years carry
this round until more contemporary
ammunition came online
in this illustration I've separated the
bullets from four
38 Special cartridges again they all
illustrate something about the great
variety we can find in ammunition that
can be useful in resolving a question
Silver Tip you've already seen is on the
left we can see the cantalore this is
one that happens to have an aluminum
jacket you can also see perhaps a little
bit of Amber wax-like material in that
cantaler that's a special lubricant a
proprietary product to keep the aluminum
from galling as that has driven up the
barrel of the gun that was one of the
technical problems in developing an
aluminum jacketed bullets that material
doesn't melt totally it doesn't burn up
it's not against the powder gases so
that may become trace evidence that can
be spattered on clothing or wiped off on
clothing as a bullet goes through how
would we use that let's say a bullet
goes completely through use my arm as an
example I get shot in my left arm
Bullock passes through my coat shirt on
out the other side but we've got traces
of what aluminum and possibly this
lubricant that we'd be able to say if we
understood and appreciated that and
talked to the laboratory but this this
injury was created by a silver tip
bullet and I know that for those two
reasons and we have other Shooters
firing at me as this hypothetical uh
assailant or victim
the next bullet's somewhat unusual that
happens to be made by federal and it has
no knurled cantalers now I've probably
used that term several times knurling
means these little slices these little
indentations that we see on the other
two all cantlers don't have to be
knurled some of them can simply be
grooves
uh this cartridge also has a cantaler in
another place on the cartridge case look
down on the cartridge case in this
particular example and you'll see a
little knurled cantaler that's again a
product identifier not that it's so much
Federal we'll know that by looking at
the head stamp but that it's a
particular loading of Federal's
ammunition so the bullet shot it's
history it's out there somewhere but
we've got this cartridge case and the
question is could the bullet we've dug
out of the side of the police unit have
come from this particular cartridge
that's one way to address that question
because another product line by federal
will either have the Candler in a
different place or none whatsoever
the next one's kind of an interesting
one also because here's an example of a
cartridge with an aluminum case the one
that is light blue this is made by Omar
Industries or Blount as they're now
called
it also has a copper jacketed bullet an
aluminum case that I've already pointed
out has been anodized in blue
that's the case with this example
because it has a very special priming
composition in it that Allah perhaps
talk about later
the bullet has a nerve Candler but it's
interesting in another way that
particular bullet has a copper jacket
completely around it and right now again
91 that's a unique process by omarc
Industries called their TMJ their total
metal jacketed bullet and the jacketing
of that bullet is absolutely
electrolytically pure copper whereas the
others will be alloyed with zinc it is
also bonded because it's a plating
process to the core the Lead Core of the
bullet so this too can be determined at
the laboratory both by microscopic
inspection and by analytical methodology
even if we just had a fragment of a
broken up bullet to be able to say this
was a TMJ a total Metal Jacket a bullet
only one company right now that makes
that so we're looking for a cartridge
that's made by CCI and it'll say so on
the head stamp of those cartridges
the last one just happens to be another
jacketed projectile with a cantler in a
similar area
and a Candler on the cartridge case
okay I've said head stamps several times
and we looked at head stamps on 22 rim
fire cartridges that's that written
information on some people might call it
the base of the cartridge technically
it's the head of the cartridge Center
fire cartridges is that one cutaway
showed us have a primer located in the
center of the cartridge which the firing
pin strikes here's some illustrations
some drawings of a variety of of head
stamps
and these are useful not only because
they Fascinate some people who've become
collectors of them but because they tell
us something
take a look you'll see two up there that
say r p 38 S and W
and if you study them you'll see that
one has a DOT between the r and the p
and another has a dash that's
intentional and there's a particular
year for that cartridge designation that
Remington went from a dash to a DOT so
it sets a point in time after which one
type of cartridge was made
and before which the other was made
how could that possibly be useful well
if we knew and we can find out when
these things were introduced
discontinued started up tells us
something about the age of the
ammunition subject claims that he took
granddad's old
rifle down off the mantelpiece never
been examined or shot in probably 40 or
50 years he didn't realize it was loaded
he turned toward his brother with whom
he'd been having an argument for some
several days and it went off
accidentally
if we were to open that gun up and it's
going to get opened up no doubt and
remove a cartridge that was only made a
year ago introduced a year ago the story
doesn't doesn't hold it can't have been
sitting around for 30 years with a
cartridge in it that didn't exist until
1990 and we can play that scenario other
way so the age of the ammunition as
derived from the head stamp can be very
useful some are much more rare unusual
than others
here's some actual head stamps drawings
are perhaps useful but in actuality
let's see what they look like here's the
one I just talked about has the RP
standing for Remington Peters it also
tells us the cartridge designation nine
millimeter Luger most American
ammunition will tell us what we're
dealing with 380 automatic 45 automatic
38 special and so on
there will be others however that are
not quite as descriptive that our
military or foreign head stamps and
we'll again show some of those a little
later I've also placed some on this
illustration that are fired so we can
now see what the primer looks like
before the cartridge is discharged and
afterwards and for some examples of that
if we go to the third one over
Winchester cartridge that's been fired
by a Glock in fact a Glock leaves a very
unique firing pin impression and breach
face signature on the primer
the next Winchester cartridge has a more
typical hemispherical firing pin
impression in it
might also notice that some of the
primers are nickel plated or shiny look
like Chrome While others appear to be
brass or copper colored again that's
intentional by the manufacturers
in this particular illustration I've
removed the primers from the two types
of ignition systems that are used in the
world one of them is called the Brock
boxer method boxer oddly enough was a
man in England that happens to be the
system that we use almost universally in
the United States and the boxer method
has a single flash hole this is the
opening through which the jet of flame
and Sparks goes to ignite the powder
when the primer is struck the burdan
named after an American who developed it
has two flash holes with a thing called
an anvil this is a raised piece of metal
between which the cup of the primer has
struck by the firing pin is pinched or
crushed in American or boxer primers
the Anvil is built right into the primer
and here's an example we're looking down
inside of three primers
or the explosive composition is located
underneath that little two or
three-legged anvil
the others I've turned up
from The View you would have if you were
a firing pit and going to strike these
in fact I've put one in here that's been
removed from a fired cartridge so you
can see a firing pin impression in a
fired primer
and finally that same primer or type of
primer with the caked gritty sort of
residue
again this may seem overwhelming at
first and very very technical but
there's a plethora of information that
arises out of these primers and the
composition that's in them that ends up
on surfaces on clothing and on the hands
of Shooters that's useful in a number of
ways here for example are three common
mixtures or formulations I've not
identified the companies because these
are proprietary products but if you read
through this list you'll see something
that's the same in all three of these
mixtures barium in the form of barium
nitrate
antimony in the form of antimony sulfide
and lead in the form of an explosive
called lead stiffenate
those three elements barium lead and
antimony survive the discharge process
so when a gun is fired
that jet of flame and Sparks that goes
through the flash hole and ignites the
powder gets rearranged all right it
explodes and burns but you can't really
burn lead barium and antimony those are
elements and they come out much like
Hairspray comes out of a hair sprayer
they are an aerosol that surrounds the
hand of the shooter and of course
creates quite a cloud of debris in front
of and sometimes to the side of the gun
and those are the elements that the
analyst in the crime laboratory uses to
characterize gunshot residue that's one
method of characterizing gunshot residue
the traditional paraffin test which is a
passe for many years was for nitrites
and nitrates
this is for the elements of the
Contemporary testing is for the elements
in the priming mixture
on the home stretch on discussing
bullets but I really need to to cover a
couple of areas that I haven't so far in
this display of pistol bullets we've got
several other new things that I'm going
to add into your repertoire of
information
the bullet on the upper left is a cast
bullet so far I've shown you a number of
lead bullets 22 bullets with and without
copper plating and some other 38 caliber
bullets those were swedged they were
literally forced into a mold under high
pressure they were extruded and formed
it's how they get the cantlering in
there
cast bullets are just that they're cast
in a bullet mole
and I've brought one of my own bullet
molds with me today
and this process simply involves taking
molten lead from a ladle
delivering it to this two-part mold
through the opening usually taking a
piece of wood to break this open such as
I have now
and then we can open up the mold and if
it doesn't drop out see a cast bullet
well I've added emphasis to that word
about three times now because this mold
is split in half has to be to get it
open that leaves a seam a very faint
seam on the edge of the bullet so look
again at the bullet at the upper left
you can see the lubricant you can see
the grooves in that bullet and they are
filled with an amber colored lubricant
we've talked about the use of lubricants
as trace evidence
but you can also see the seam from the
mold that casted that survives discharge
we can usually find that somewhere on
the bullet
that again is useful because if we have
a shooter that's using hand-loaded
ammunition it may indeed be loaded with
such bullets we may have a supply of
lead at his residence that could be
compared with the composition of the
lead in a cast bullet and it actually
may be a unique formulation given the
type of scrap wheel weights and metals
that he's made it from
and also on occasion identify the bullet
mold from which the bullet was cast the
imperfections that are in that mold are
being replicated in the cast bullet and
if we go down into areas such as the
base of the bullet
those lubrication grooves that usually
survive impact we might be able to find
that sort of identifying information and
even though we can't match the gun let's
say because the bullet's too damaged we
might be able to say that bullet came
from that casting mold which is in the
workshop of the defendant
okay some other bullets here here is
indeed a swedged bullet right next to it
formed by simply Extrusion the neural
cantaler I've put up here another cast
bullet for you they don't all have to be
round nose we've got one here that's a
semi wad cutter that I discussed earlier
how do I know it's cast look at the seam
this one has a black lubricant in it so
even the color of the lubricants may be
different and again be a clue this one
has a gas check on it I talked about gas
checks the previous one on the left does
not
next to that is again at this time a
unique item this is made by the hornaday
company
and it has a stippled some might call it
a knurled texture in which they've
placed the lubricant so the waxy
lubricant that keeps the lead from from
galling or letting up the bore of the
gun is actually impregnated in all those
little diamond shaped checkerings
again it would identify the product if I
found and I have encountered this
particular bullet in several shootings
as a hornaday bullet but there's
something else that's fascinating about
this bullet in addition to a lubricant
it has a mineral called pyrophylite it's
a mineral similar to talc that doesn't
burn it really doesn't rub away that
well so now after firing such a bullet
we've got pyrophylite residues in the
barrel of the Gun there's still some on
the bullet and if it goes through my
clothing or anyone's clothing for that
matter or a wall around that bullet hole
in a material called bullet wipe will be
traces of pyrophylite even though the
bullet may go on out through the window
or curtain and across the countryside
never be found I've now got away if I
know something about ammunition to say
that particular Bullet Hole was a
hornaday bullet because of the presence
of the pyrothalite in the bullet wipings
now next year someone else may infringe
upon their process but at this moment
and that's why again the purpose of this
tape is one must remain current as to
what's going on in the industry here's a
way to resolve a situation of what kind
of bullet or what shot went through it a
wad cutter the next bullet we've already
seen another full metal jacketed bullet
a full metal jacketed bullet with a
cantalore here's one of our silver tip
bullets in the bottom left row and now
we can start to see a few other features
some of these companies will Notch the
bullet jacket to help it expand upon
impact in in tissue or game animals
um that's often survives and like the
Remington scalloping that I already
described could allow us to resolve one
company's Bullet From Another just by
finding this sort of class
characteristic on the projectile
and we've got a couple more here here's
a nine millimeter a contemporary police
loading the subsonic nine millimeter 147
grain bullet third over from the right
on the bottom row
uh jacketed semi-wide gutter or target
shooting primarily and another one of
our silver tip bullets that one happens
to be in 45 automatic and it happens to
have an aluminum jacket the same bullets
you just saw have now been turned up in
so we can look at the nose shapes we
could only see them in profile a moment
ago
and here we can see some of them are
Hollow pointed some of them have the
notching that's a little more visible
and apparent some of them have other
features such as the wad cutter almost a
ring-like feature in that particular
projectile
I'm going to go through to sort of bring
together a distinguishing Brands where
everything else is the same in these
seven
examples of 357 Magnum ammunition the
bullet weight is the same 158 grains
but we have at least we have four
companies represented and in one
particular line we've got three entries
from the same company Federal
here are these same cartridges one
example from each where I've pulled the
bullet out of the cartridge and set it
beside it we can look at the head stamp
if we wish to if you wish to go back and
find this area in the tape and look at
it more closely
here we can look at the base of each of
these bullets and see some differences
even though the weight and the caliber
is the same and again the base of course
is one of the areas that survives best
when bullets hit very hard objects
some of these cartridge cases have case
can allures others do not I've already
mentioned the potential importance of
that
here's a little closer view of each one
of these
projectiles bullets pulled out of the
cartridge case and then I've written on
the cartridges so we can go back and
forth notice some of the things the
number of cantalors the position of the
cantalore the general features of the
bullets surface whether it's jacketed or
lead
scalloping in the case of the Remington
that I talked about earlier versus a
straight Union between the lead and the
jacket the presence or absence of
notching all of these features often
survive substantial damage upon impact
okay let's start bringing the other
components together here's a
disassembled
should be able to spot it by now a
Remington bullet it's got a scalloped
jacket cantalore
this is the propellant charge smokeless
powder nitrocellulose in a particular
form in this particular round of
ammunition the cartridge case nickel
plated brass
and here are two fired Remington bullets
so the type you just saw but there's
something different between the two look
at the bases of them one of them has a
stepped base as the industry calls it
there's a little indent on the base of
the one on the right
the base of the Remington bullet on the
left is smooth or flat
that's a product or manufacturing change
that we have a date for it occurred on a
particular date where they retooled and
Remington now makes that bullet that
would otherwise look indistinguishable
with a flat base
so what
well a very famous case in Utah where a
man was shot to death confronting the
police
and there was an issue about whether he
was gunned down by police officers from
agency a b or c
they were all carrying Remington 357
Magnum ammunition with this particular
weight of bullet they were different lot
numbers of ammunition and fortunately
the investigators in the shooting
response team
saved secured examples of each agency's
ammunition as well as what they were
carrying in their belts and in their
service revolvers
one agency was carrying Remington
ammunition that was a little older than
the other so if I had a bullet that was
badly damaged and we expected them to be
very damaged given the situation in this
particular case I could at least say the
bullets with the step base were being
carried by agency a and the Very
otherwise same bullet same powder same
weight same kind of guns being carried
by agency B had the plane base
both have of course the scallop jacket
and everything else the same
let's go back to these bullets we just
looked at I've talked a lot about firing
bullets and yet I haven't shown you what
they look like after they get fired here
are three of our examples up above a
lubeloy plated lead Winchester brand
bullet on the upper left
a federal bullet in the middle a
jacketed soft point bullet and finally a
Remington bullet all of these are the
same weight same caliber below is a
fired bullet so you can see that that
thin copper plating that lubaloy finish
is very fragile and much of it gets
rubbed or scuffed away during the
discharge process
in fact you can faintly see the vestiges
of the land and groove or the rifling
impressions on that bullet they're much
more conspicuous on the next two
candidates because that's a fairly hard
copper jacket not nearly as fragile as
that lubali plating and the federal
bullet shows very nice rifling
Engravings we can see three land
Impressions on the bullet the next one
the Remington bullets a little more
difficult to see but it's it's clearly
striated it's clearly gone down a gun
barrel and of course as you can see it's
expanded it's expanded very nicely it's
expanded just the way the company
intended it to but we can still tell
with a little experience that that was a
scalloped jacket these petals have just
rolled back very nicely so we can still
see their their physical shape Just In
Reverse just turned inside out
okay let's bring it in bring a cartridge
into the gun now I've gone back in this
illustration from the hand loading
manufacturers Institute a rifle
cartridge so we don't forget what a
rifle cartridge looks like a
bottlenecked cartridge but the mechanics
are still the same we've got a primer
Center fire it's about to be struck by
the firing pin flash hole allows the
flame to go through and ignite the
propellant charge which we can see it
looks like a bunch of sticks in there or
little particles and our jacketed soft
point bullet
microseconds later after the discharge
of that primer the powder is ignited it
carries its own oxygen the misconception
is you don't need air inside the
cartridge case nitrocellulose has its
own oxygen supply think of it like a
solid propellant rocket
there's a number of other things in
there we're going to be interested in
but basically that solid propellant
which can be in a number of forms
creates heat and pressure really after
pressure to force the bullet up the
barrel where it engages the riflings
takes up the images of the riflings or
the lands and grooves as they're called
and finally emerges from the muzzle with
noise because of the expansion of gases
which can be suppressed with suppressors
and sometimes with light and of course
with a lot of residue that we're going
to be very interested in in a few
moments
I've talked about propellants the
traditional propellants that are
depicted in in western movies and period
pieces from the last century from our
Revolutionary War was black powder black
powder is a mechanical mixture of sulfur
sodium or potassium nitrate and charcoal
if you get it wet it comes out of
solution and it's no good
on the right of this particular slide is
what black powder looks like it came in
several granulations this happens to be
3F granulation under a microscope it
simply looks like little pieces of coal
on the left is a new product new within
the last decade called Pyrodex and
pirate X has the same thing black powder
has in it plus other constituents it's
changed its category as far as the DOT
regulations it's also got a different
physical form but from a Firearms
examiner standpoint it leaves different
Trace residues in the barrel of the gun
and on the clothing of the shooter in
the hands of the shooter and of course
on around bullet holes and its physical
appearance is quite different you might
think well black powder guns are
something of the last century as I just
said their companies making replicas of
these firearms and there can be
accidents and have been accidents with
replica guns and there have been very
few but there have been some criminal
offenses carried out with black powder
firearms and I've personally worked
three or four of those myself so
distinguishing whether the residues are
black powder or Pyrodex is one of the
first steps in that analysis
about the turn of the century a new form
of propellant came into existence and
that was the development of smokeless
powders made primarily either from wood
meal or later cotton by nitrating it so
Nitro cellulose as it came to be called
now if we could see some nitrocellulose
here today it would basically look like
a light Amber material
in the manufacturing process it is soft
and can be excrete extruded through a
thing called a spinnerette much like
macaroni or spaghetti so if we look at
this next illustration this is a
contemporary
nitrocellulose or smokeless propellant
called tubular powder the only reason
it's gray is because it has a graphite
coating to feed through the powdering
measures more easily and of course to
dissipate static charges in cartridge
cases
but these little pieces of black
macaroni have a central hole or
perforation through them and that has to
do with changing the burning
characteristics of this solid fuel
the length and diameter of these
particles can vary so there's a whole
series of these tubular extruded
propellants called the IMR series they
are primarily associated with rifle
ammunition
we can take that same methodology this
Extrusion of this nitrocellulose through
a spinneret and just set the cutter so
it chops them in shorter pieces to the
point we finally get a little disc
and we have two choices a disc with a
little hole in it or Central perforation
such as you're seeing in this
illustration this is Alcan 120 a pistol
powder that looks like a little gray
disc with a hole in it and that would be
inside of a for example a pistol
cartridge
after it's fired some of these particles
will not burn in fact that's true in
every one of these examples I'm about to
show you here's an example of a disc
flake powder with no Central perforation
this particular one happens to be known
as unique uh with a capital u it's a
brand name that's used by many hand
loaders of pistol cartridges in fact
close inspection of some of these
particles one can even see the tool
marks of the cutter bar that shave them
or cut them as they were extruded
through the spinner wrap
this form called lamel's l-a-m-e-l-s is
one that's associated with European and
Scandinavian manufacturers no one in the
U.S to my knowledge has ever made or
makes now this physical form again of
the same material nitrocellulose these
lamels take the form of little squares
or diamonds and again some of these Will
Survive discharge and show up as gunshot
residue well from what I've just told
you associated with European or
Scandinavian ammunition can be a clue if
we were to find such residues around a a
bullet wound or a gunshot injury
another form of nitrocellulose came into
existence in the 1930s developed by Olin
what Olin did was take normal extruded
tubular nitrocellulose and form it into
a gelatinous mass in a colloidal
suspension so it Formed just like oil
and water little balls hence the name
ball powder and it too is gray or black
because of the graphite coating they did
something else with ball powder they
Incorporated another
constituent another explosive a true
explosive in this case nitroglycerin but
dissolved in nitrocellulose in certain
percentages it doesn't explode it burns
and that's an important distinction all
gunpowders burn they don't explode they
have to or you'd burst the firearm ball
powder can be truly spherical such as
this example h870 again a canister
powder reloading powder occasionally
you'll see an oval particle but
basically these are all spherical
or it can be flattened
and here's blc2 again a hand loading
powder where these spherical balls were
passed between rollers and they were
flattened slightly that changes the
burning characteristics and this is an
important thing in the industry to match
the available powder space with the
bullet weight and the barrel length to
get the right pressure curve and the
right velocity without bursting the
firearm or basically having a squib load
a bullet that goes part way up the
barrel and stops
another example of
egregiously flattened ball powder in
fact the industry will often call this
cracked ball where the balls the
spherical balls have been so flattened
that now they're basically flakes
and they crack around the edges in fact
there are a few members in here if you
hunt through them you can find these
little
checks or cracks in the edges this
particular one is Winchester 231 to the
hand loaders out there
again the fundamental thing is we've got
chemistry nitrocellulose and
nitroglycerin in double bass powders
just nitrocellulose and single base
powders plus additives graphite and
deterrence other Coatings that survive
the discharge process and some some
amount some small amount and end up in
the barrel of the gun in the chamber of
the gun in the fired cartridge cases and
on anything nearby and by nearby I
typically talking in terms of a few
inches maybe a foot or so and even the
physical form that I've just described
for you of some of these particles May
survive and can be Associated back with
again ammunition manufacturer or some
other trace evidence association with a
responsible gun
okay I'm going to illustrate the
difference the the characteristics and
the way they burn and leave residues
between smokeless propellants and the
traditional black powder of the last
century and to do that I've simply
stretched out a fine line here of
smokeless powder the one I particularly
used in this case is unique the disc
flakes without the perforation you saw a
moment ago
which lead up to a small charge of 3F
black powder now the 3F just has to do
with the granulation size now what I'd
like you to look for is the clean
burning characteristics of the smokeless
powder the virtual lack of any smoke
and the amount of residue that will be
left behind and then what occurs when we
get to the the black powder
there's smokeless powder
and black powder
now the reason they both burn fairly
slowly compared to a gunshot is that
they were unconfined there was nothing
resisting the development of that heat
and pressure put in a cartridge they're
both going to burn what seems like an
explosion
but looking at this we have just a Amber
residue where the smokeless powder is
located we have a lot of black soot
where the black powder
burn or deflagrated as the technical
term
now let's bring all of that information
together
and look at this illustration this
drawing where I've
summarized the sources of
of particulates of chemical constituents
of debris that issue out of a firearm
this illustration gives us a top view
of a revolver
here with this cult python I'm
illustrating the same view we have in
the drawing we're looking down on the
top of it in a revolver we've of course
got a revolving cylinder
the cartridges and these are dummy
cartridges so the cameraman doesn't uh
totally
get upset with my pointing it at the
audience we can see that there are
cartridges in these Chambers we
basically got a load indicator here in
that we can see the cartridges in loaded
Chambers but the point I also want to
make is those projectiles those bullets
when they're fired
have to get from this cylinder into the
barrel and to do that they have to jump
across an opening an air space it's very
small one but nonetheless
there's an area where they're
unsupported and they're open to the
outside that's called the cylinder Gap
and we will get a fan of gases sometimes
of light and debris coming out of that
cylinder Gap some of it's bullet metal
some of its powder residues and those
barium lead and antimony constituents I
talked about earlier most of them of
course that don't burn or are partially
consumed are going to go out the muzzle
but the point of spending a fair moment
here with you on cylinder Gap is just
this let's say I'm sitting in my car I'm
an assailant and an officer comes up to
write a ticket and I'm going to murder
the man
if I'm holding the gun in a concealed
position close to me like this I'm going
to have a Scorch a deposit of debris
from the cylinder Gap and some
additional from the muzzle and I've got
two things here now to work with I know
the barrel length of the gun even though
I don't have the gun yet from the
separation between these two deposits
and I also know that I'm probably
dealing with a revolver as opposed to
a pistol or a semi-automatic
a firearm such as this
where there is no opening to the outside
the cartridge is in the chamber which is
integral with the barrel the primary
source of gunshot residues and a firearm
of this design are here at the muzzle
okay let's go back to the revolver
situation in the illustration and I'm
now holding I've got two places this
material can come out if for example we
had this
shoved in a pillow or a blanket or
something trying to use it as a muffling
or silencing device we can even end up
with patterns like this
and here this piece of
cotton was simply draped
not drawn taut but simply draped over
the revolver
and we end up with two scorches out each
side the top being shielded by the back
strap
another example of how we'd use that an
alleged accidental discharge in a
holster
if the gun's truly down in the holster
and it's a revolver we're going to have
two deposits and we'll know exactly
whether the revolver was fully in the
holster or Not by where those cylinder
Gap deposits are located compared to the
dimensions of the gun
here's an example of a person's shorts
with two gunshot residue patterns on
them and no Bullet Hole we can see a
faint one here near the top
and a much more intense one down near
the pant leg the account in this
situation was one of the guns slid off
the bed or the seat of the pickup truck
hit the step shot them in the foot that
clearly isn't the case and if we look at
the Reconstruction of this shown in the
slide
where we have the gun juxtaposed
alongside these patterns you can see
that the intense Flash and soot material
is from the muzzle
and the more subtle flash is from the
cylinder Gap and the Blank Spot in
between is a representation of the
barrel length of the gun in this case of
course we have the gun so we already
know that but it does allow us to show
the position of that firearm at the
moment of discharge and once again we
could do test firings to hold the gun a
half an inch an inch two inches away
from similar material and probably get
down to within plus or minus an inch of
the actual distance it's certainly not
over on the running board of the truck
when it's discharging so there's a final
example of gunshot residues in the
horizontal plane rather than the
straight on orientation and how they can
be used to reconstruct the orientation
position distance of the gun at moment
of discharge
okay some additional illustrations of
the value of gunshot residue in this
illustration I've tried to summarize the
fact that we've got particles
some of them are bullet metal we've got
an aerosol of barium antimony and lead
with American Center fire ammunition
we've got other materials in foreign
ammunition incidentally that
characterize it as such that are
different from what we see in American
ammunition we also have [ __ ] material
basically carbon the material you saw in
my fingers from the black gunpowder and
even to a lesser extent from smokeless
gunpowder and these things come out of
the muzzle of the gun much like a
pattern of shot in miniature the
particles distribute themselves in
somewhat of a conical fashion as they go
across distance they lose energy and
velocity they spread out the soot will
have a point at which it cuts off and no
longer leaves a deposit on clothing
here are a couple of interesting
examples that again
look at the difference between Smokeless
propellants in revolvers and black
powder the upper figure from one of the
gun magazines shows us a revolver which
has that cylinder Gap I've discussed at
the point before the bullet emerges from
the muzzle but after it has crossed the
cylinder Gap and if you look at that
illustration in some detail you'll see
two flares of of foggy-like material
coming out of the cylinder Gap the lower
picture of
fellow who specializes in black powder
guns in one of the trade Publications is
shooting a black powder revolver
although you're hard pressed to
determine that because his hand and the
gun are completely engulfed in black
powder fouling so if we had had a way to
control things I'd really rather have
shootings with black powdered guns from
a trace evidence standpoint or from a
gunshot residue standpoint because they
create massive amounts of it by
comparison
something else if I had just fired this
revolver and only fired it once
if it had been reasonably cleaned
sometime in the past
cockat
fire at once material coming out of the
cylinder Gap that you've already heard
about on out the muzzle
that will create a smoky ring sometimes
called a flare or a Halo on the face of
that particular chamber the one that was
under the hammer
that will tell me or the way I would
interpret that in the slide you may be
now looking at is this gun has been
fired once
since last cleaning
something else we've talked about a
revolver and how the cylinder Works
let's say
here's my account I'm talking to the
police officers I'm claiming it's an
accident that I was simply handling the
gun I didn't realize it was handed to me
cocked I'm unfamiliar with guns I
touched it and it went off
all right where is that fired chamber
I'm going to let go of the trigger
nothing moved other than the hammer the
fired chamber
in the cylinder is in line with the axis
of the barrel it's under the hammer the
investigator if prints are not an issue
and they're not I'm saying I held the
gun no point in processing it for prints
I fired the gun but I didn't mean to all
right the astute investigators should
take something like a Sharpie marking
pen something that is not going to
deface the firearm
even white out can be used and place a
little tick mark
on each side of the cylinder in the gun
on the gun as found now once we've got
it documented photographed in place
marked the cylinder of a revolver now we
can open it up
and look at where fired cartridges are
we'll talk about marking evidence a
little more in diagrams but my point is
look at the difference and look what
happens if we get in you officers out
there get involved in this mad rush to
secure the weapon
I actually shot the guy and I meant to
just shot him
and he wasn't going down fast enough so
I thought about it again and well no
he drops to the floor I just cycled that
cylinder if you missed it run it back
and take a look again the fired
cartridge is now one space over
police are going to come
the neighbors heard the shot I'm going
to call it in as an accident if I'm not
thinking and few criminals are clearly
I'm going to let that hammer down
and then either just drop the gun on the
floor or set it down
if I rush in as an investigating officer
where's the gun where's the gun grab the
gun up
get the cartridges out of it
I've lost that opportunity I'll now
never be able to confront that person in
the LIE
in the
in the fraud that he's perpetrated on us
and and we're doomed
the flare is that Smoky residue that's
created on a relatively clean gun from
the discharge and of course if this
example had been fired several times
we'd have overlapping flares and we can
actually see that at the laboratory with
appropriate lighting that one precedes
the other or there may be a space
between them where there's been a
misfire
let's go to automatics they don't have
cylinders that rotate the cartridges are
in the actual Barrel
where the firing is going to take place
so they don't have to jump across an
airspace
but we still get substantial amounts of
gunshot residue in this remarkable
photograph also from one of the popular
gun magazines is a semi-automatic pistol
not too different than the one I just
showed you
where we can see the slide and Barrel
are still
forward in other words it's still in
battery as the armor would say
we've got a little bit of flash a cloud
of [ __ ] material that's going to get
much bigger in the next few microseconds
and although it's not clearly apparent
the bullet is actually In This Cloud of
debris it's right at the leading forward
end
of the discharge
now this may be a little hard to
understand or see at first but you're
looking at a highly magnified picture
that I took years ago in the crime
laboratory through the microscope
looking right down inside the Gun Barrel
and this illustrates again an important
point about the powder particles in
their physical form themselves you're
looking at a particle of unburned ball
gun powder
adhering to the interior the bore of the
gun in a pistol that's been fired
that's historical information the last
shot if there were more than one the
last shot fired in that pistol was with
a cartridge loaded with ball powder
a quick another example let's say we
have a bar room shooting two subjects
both armed with this happened to be a
380 automatic both armed with 380
automatics one shooting Winchester
ammunition one shooting Remington
ammunition they both admit shooting
their guns
toward the decedent in the to the extent
that one was going to frighten him by
firing off to one side the other was
going to do the same but apparently
screwed up because the man's got a shot
right through him but there's my point
it goes all the way through the bullets
never to be found
if we've got gunshot residues on the
clothing
we can say well Remington has disc flake
powder in it by way of an example and we
know that because the cartridges are on
the floor those can be matched back to
the gun in a semi-automatic quite easily
the other man has fired Winchester
cartridges and some ball powder residues
in the bore of his pistol with the
population of two it has to be a or b
even though we don't have a bullet but
we've got residues I can tell you who
fired that shot it's the man with the
cartridges loaded with ball powder and
you can play that scenario other ways
but just imagine what will happen
if this gun is picked up for the pencil
stuck in the muzzle as depicted on
television that singular particle of
powder is history
I'll never see it again and we're now
precluded we can still match cartridges
to the guns but we've got to establish
which gun caused the injury
powder particles from those physical
forms I just showed you can also Express
themselves right in the base of the very
bullet earlier I showed you some full
metal jacketed bullets with exposed lead
bases in some combinations of powder and
full metal jacketed bullets the powder
particles will actually print their
image in the base of the bullet and
here's an example from an actual case
this is still an unsolved case incident
we have a long distance shooting with a
30 M1 carbine and you're looking at a
split view through a comparison
microscope in the top view is the bullet
with little imprints of the type of
propellant that propelled that bullet
and this was unique because 30 M1
carbine Ammunition by manufacturers has
never been loaded
that I could ever determine with this
type of propellant but one commercial
hand loader in Phoenix Arizona loaded
600 rounds of this ammunition and sold
it to six different people
so in all likelihood there's our
investigative leads we've got six hot
contenders out there that bought 100
rounds each of what most likely was the
very ammunition used in the shooting the
bullet was made by hornaday the
propellant by Remy by Dupont and it was
a
4227 as I recall for the hand loaders
out there and several of these this is
the type of extruded powder that's a
little short spaghetti or macaroni
pieces that have the central perforation
some of those actually can be seen in
the base of this bullet and we could go
through the same scenario with the
lamels the little diamonds or squares
disc flake and so on and see this in
some instances
the residues at the muzzle
here's a piece of cotton a typical
witness panel material that's used by
criminalists and Firearms examiners
where we will set the distance and I'll
use myself again as a model
where we'll set the distance with a
machine rest or a ransom rest between
the material and if this jacket were
shot I'd ultimately use other pieces of
the jacket and pick distances two inches
four inches six inches and so on and
actually fire patterns such as the ones
I'm about to show you
and compare those
with the actual evidence pattern and
typically if we've got a pattern it's
telling us already that we're dealing
with fairly close proximity discharge a
few inches or feet
and by the intensity and diameter and
the distribution of powder particles in
that pattern we can typically set a
standoff or separation distance within
plus or minus a couple of inches
and that's very useful even if you think
that's a serious error if the issue is
I shot him from some distance or he was
coming at me and we were struggling over
the gun and I jerked back and it fired
it's the difference between inches and
three or four feet and that's easily
reconcilable and resolvable by this kind
of testing I'll just run through a
couple so you can get the idea of how
these change as the distance increases
very close we're going to have a lot of
soot and the powder particles are going
to be intensely co-located Around The
Bullet Hole
as we back off that [ __ ] cloud because
it's very light in its density and the
weight and the energy of those particles
dissipates and loses its velocity
so it's just going to start leaving a
very faint deposit as we get out to well
typically four five six inches and so on
the powder particles the unburned
particles and those various physical
forms we talked about the example I gave
you earlier was like shot in miniature
little particles going out in a conical
distribution those will impinge upon
skin and if it's close enough they'll go
right into skin that's called stippling
if it's on clothing they'll stick into
sometimes perforate the first layer and
be found in the second
but they will also be deposited on the
first layer and careful handling of
course is important so the investigators
don't dislodge them but if that's done
then we now start looking at a pattern
of powder particles and less and less
soot so in this depiction you've got
mostly powdered particles distributed
over about a five or six inch diameter
and if we go in very close this is a
photomicrograph we can see the Bullet
Hole
and again if your resolution on your
camera is very good or your television
you can spot some of these as disc flake
particles now they look yellow
instead of gray because that graphite
coating is burned away but the physical
form is still still there
I talked about I mentioned the Bullet
Hole you might notice a faint
smudged Ring Around The Bullet Hole
that's what will ultimately end up with
at Great distance it's called bullet
wiping even in a clean bore if I
scrupulously clean this Colt Python or
this 45 automatic here today so that
bore was mirror clean
with a dry patch and fired a bullet
through it some of the gases will sneak
by that bullet
there'll be some abrasion some galling
of the bullet metal against the steel
barrel and between those two sources
will still end up with a faint ring
around an entry hole that's called
bullet wipe of course it's even more
prevalent with a fouled bore
but that's useful for several reasons it
can tell us that the hole really is a
bullet hole I mean there may be a bunch
of holes in a t-shirt or a curtain
hanging in a room that looked promising
as bullet holes the bullet wipe will
resolve that that's one way to do it
that bullet wipe has lead in it from the
priming composition the lead stiff Nate
even though a copper jacketed bullet may
have been used and where copper jacketed
bullets are used there's also copper in
that material and there are chemical
tests that I'll show you in just a
moment that can be used a very simple
technique to develop out the traces of
copper and the traces of lead in a
suspect hole in a hole we think maybe a
bullet hole but we want to confirm in
the case of synthetic fibers polyester
nylon for example the passage of the
bullet will actually melt the ends of
the fibers and those can be examined
under a polarizing microscope and
verified as a bullet hole if for example
this garment went through the laundry
and were washed or laid out in the rain
for weeks or months before a body were
found there's another way
to verify the hole as being a bullet
hole it also tells us Direction in this
view I finally zoomed in about as close
as I can with the microscope I was using
that day and we can see the disruption
of fibers a pretty nice bullet wipe
along the bottom of this bullet hole and
again
identifiable particles of disc flake
powder without a central perforation so
now I know a lot about the ammunition
that fired this particular bullet
insofar as the kind of propellant
I mentioned bullet holes through cloth
and wiping and the description I gave
you was a person with clothing you might
think well that occurs simply because of
the resistance of skin or muscle or
something behind it one will get bullet
wipe even with free hanging cloth so a
curtain and that's the illustration I'm
giving you here these pieces of cloth
were hung just free hanging off of a
hanger oh about a foot apart or so and
the point here is the first cloth to be
perforated is the one that will have the
predominant if not all the bullet wipe
on it anything after that just like the
name suggests it's been wiped off the
bullet so now we can not only establish
direction of Entry but sequence
by the presence or absence of bullet
wipe
and this illustration was an example
where a total metal jacketed bullet
shown here in other words it has no lead
on it exposed just copper was fired
through this piece of cotton and then
another piece
about a foot away
this is a shot as I just described to
you a clean bore shot with a nine
millimeter full metal jacketed bullet
and here again in this Bullet Hole
number one is the clean bore shot with
very obvious bullet wiping around it
and the description of the ammunition
and so forth is there for those who are
interested in that sort of thing
now this probably unexciting slide is
the test for copper test for copper is
called a dithio oxamide test and it's
done by a transfer technique of Simply
taking a moistened piece of filter paper
with a dilute ammonia solution
pressing it against the putative Bullet
Hole pulling it away spraying it with a
reagent called diethyl oxamide which is
specific for copper it forms this sort
of dingy gray green reaction product the
dot was simply a way for me to locate
where the hole was before I lifted this
away
a more useful and interesting test is
the sodium rhodesianate test for lead so
I've got a choice I can or I can do both
of them if both are going to be done the
copper test the dithioxamatist must be
done first then the sodium rhodesianate
test for lead this test is useful in
other ways this test being the one for
lead because it picks up the lead from
the primer it picks up lead smudged on
the bullets such as you're looking at
here from just the wiping and of course
if there's this aerosol of lead that's
deposited at very close range on
clothing we can develop it out again by
a transfer technique with Filter paper
and it's lasting we haven't destroyed
anything we simply like raising a
fingerprint developed a print of the
guns discharge Products off of the
clothing
I want to stop now and
consolidate how Firearms work in
combination with the ammunition that's
made for them and we'll recall we have
two basic types of metallic cartridges
rim fire cartridges the 22 Rim fires in
short long and long rifle
and then Center fire cartridges with the
primer in the center portion of the case
and I'm holding here some Center fire
cartridges for revolvers semi-automatic
pistols and rifle cartridges the last
two customarily will be a long cartridge
with a long pointed bullet one of these
is a tapered cartridge the other a
bottleneck cartridge let's start with
some common a common 22 that probably
many of us shot as a child a bolt action
rifle
the magazine
to hold the cartridges is often a
tubular Affair under the barrel and the
area I've opened now is the area where
the cartridges the 22 rim fire
cartridges would be inserted many of
these guns will handle all three the
short long or long rifle
some are simply chambered for 22 long
rifle the longer cartridge they would
then be fed by working the bolt out of
that magazine
up into the action
and then by pushing the bolt forward
loaded into battery or into the chamber
bolt locked closed and depending upon
design
or where the safety is we may have a
safety to disengage and fired
the bolt face has an extractor a piece
that will pull the fired cartridge out
of the
chamber
that will leave often leave a mark on
that rim on the rim that I discussed
earlier there will also be a piece
called an ejector this is some sort of
metal fixture that must strike the
cartridge and knock it clear the
mechanism so that we can load the next
round into the chamber
another common design
in this case happens to be in a center
fire rifle format is a lever action gun
again we pull an ammunition Supply from
some Source in this case a magazine
that's built into the action of the gun
cartridges are brought up by operating
the lever and again some sort of breech
block something that will hold the
cartridge in the chamber and prevent it
from blowing itself out of the chamber
secures it and that area will again have
to have some sort of extractor to pull
that cartridge out an area where marks
will be left some sort of ejector to
knock the fired cartridge clear and of
course the firing pin to discharge it
the firing pin striking either the rim
of a rim fired cartridge or the primer
in the central location of a center fire
cartridge
okay for the next example a pump gun I
have a shotgun although it could be a
rifle there are a number of rifle
cartridges chambered or designed to work
in this fashion and in most any police
action picture we've seen some kind of a
pump shotgun but the principles are the
same a breech block to hold the
cartridge in place an extractor an
ejector to remove it and to knock it
clear the mechanism and in this case
we've again got a tubular magazine under
the barrel of the gun to hold the
ammunition Supply
we could of course have a single shot
firearm where there is no magazine
but that's fairly logical
here's a semi-automatic rifle made by
Ruger very similar in fact it's called a
Mini-14 to an M14 in the military and it
has something a little different a
detachable box magazine call it a clip
if you like but I won't it should be
called a magazine the ammunition
inserted here forced upward by Spring
tension and like the other Firearms I've
just Illustrated will be fed into the
mechanism as the bolt is allowed to move
forward
and in this case since it's
semi-automatic each firing or each pole
of the trigger will cause the mechanism
to cycle by one of several means in this
case by gas heck the fired cartridge and
load the next one in as long as we have
ammunition we can keep firing until the
ammunition Supply is exhausted
there's another type of firearm that
occurs in both handguns or pistols and
shotguns called a break open design
and in this type of design the
cartridges are inserted manually and
after firing or even before if you wish
to unload the piece it's broken open
and the cartridges extracted these of
course being dummy cartridges
this is useful to talk about briefly
because there will be marks oftentimes
left by the firing pins dragging across
these cartridges once we open the gun up
so finding such a cartridge at a scene
with a firing pin scrape or drag Mark
tells me much about the mechanism if you
go back and look at every mechanism I've
shown you they work in a reciprocating
fashion forward and back here we've got
something that breaks open just like the
name suggests a break open
of drag Mark will only occur in that
kind of format so I've I've got a clue
the minute I see that and that's
something you can see right at the crime
scene with good close-up Vision long
before I have the gun I have something
that tells me basically what I'm looking
for and by way of the design of the gun
let's look at some handguns things that
we usually encounter more often than
long guns and review revolver with its
cylinder now this is a swing out design
a typical police type firearm a
contemporary firearm the cartridges
and again these are dummy cartridges
today I'll just take a couple
are loaded into the chamber you've
already seen that but they're secured
there held there by a rim and the way I
know that and the way I can tell that is
I can look at it for one but you can
feel the extended rim on a rimmed
cartridge rimmed cartridges are rimmed
because they're designed or originally
intended for revolvers if we didn't have
that Rim the cartridge would just
continue to go on down into the chamber
this is again useful because the design
whether it's rimmed or rimless of a
fired cartridge tells me something about
the kind of mechanism that it uses so
here's four rounds dummy rounds loaded
into our Swing Out cylinder revolver now
we've got two ways to fire this type of
gun we've got what's called double
action and although it may seem single
at first it's really double and I'll
explain why this is double action
discharge pulling the trigger
accomplishes two things
it [ __ ]
and discharges the pistol really you
might even say three things it also
revolves or rotates the cylinder single
action
would be a situation where I've at some
point cocked the piece
and now pulling the trigger accomplishes
the single act of firing it
Hammer Falls
again single action would be like this
double action like that
some revolvers and some pistols for that
matter are strictly single action that
is you have to [ __ ] the hammer back some
external Hammer to fire it others are
like this you have an option and the
prosecutor or any attorney's standpoint
doing this readying the gun in single
action
they would argue is a premeditated act I
tend to agree you have to think about
that it doesn't happen automatically now
we may have other guns
that are double action or even single
action but that do not have an external
Hammer here's an example of a little
inexpensive 25 automatic
pistol cartridge you'll see there's no
hammer on this firearm and right now
although I've checked it of course you
as an observer or a detective wouldn't
be able to tell if it's loaded
we can remove the magazine I've done
that
not the clip and see that there are no
cartridges in it but let's assume there
are some cartridges in it I still don't
know that it's necessarily unloaded and
this has been a popular defense in many
cases the person took the magazine out
and assumed the pistol was unloaded but
there easily could be a cartridge in the
chamber some Firearms will have a load
indicator this one does not
so I'd have to then retract the slide
this piece that I've just moved to allow
the extractor to work and pull any
cartridge that's in there out
looking at it from sort of the other way
the internal mechanism in this gun is
not a hammer but rather a thing called a
striker basically just like a nail or a
pin that's under spring tension it's now
been cocked so if I load this pistol
with the exception of activating some
sort of safety it's ready to fire I
don't have to [ __ ] anything
and it does not have what's called a
magazine safety some Firearms will have
a safety mechanism that if you remove
the magazine it can't be fired
these features are all of interest and
importance in reconstructing or
evaluating a defendant or an arrestee's
claim particularly an alleged accidental
shooting cases occasionally it may be
true but the features of how the gun
work is works of how guns work are not
something I expect every detective or
officer to know in fact I don't know how
every gun works but something that once
it's documented photographed and
properly collected can later be
evaluated if we have an account or an
explanation
gone up a little bit in caliber in this
pistol again we've got a slide in this
semi-automatic pistol we've got an
external Hammer that we can see
that would be cocked if I worked the
slide and loaded the gun or I could
manually [ __ ] it
and then again it's of course unloaded
this does not have a magazine safety so
if I head around in the chamber even
though I had no magazine in it it could
be fired and this gun has a double
action capability that the last pistol
did not again by that I mean notice that
the hammer is down but I can simply
reach in pull the trigger and like the
revolver I showed you fire This Gun For
the first shot when that fires the
action of the powdered gases will drive
this slide back
eject the fired cartridge under spring
tension it will fly forward
the hammer is now cocked and if we had a
magazine with ammunition in it we've got
another round in the chamber and since
it's semi-automatic I have to let go of
the trigger just enough to allow a thing
called the disconnector to function
now I can fire it so I can keep doing
this
as long as the ammunition Supply lasted
we've talked about the cylinder Gap in a
revolver and how the bullets must jump
across that opening
and how the cartridges are held in there
I now want to look at a another
semi-automatic pistol a government Colt
45 automatic
and I've removed the barrel from a like
gun so you can see the distinction I
talked about earlier and this will
become useful in a moment
when we look at the markings on bullets
here's a barrel out of a government Colt
45 automatic and here's a cartridge for
it no revolver or no cylinder but rather
the chamber is machined into and a part
of the actual Barrel so this cartridge
goes in and it finds its seat headspace
being the technical term but Finds Its
proper position simply by running up
against a shoulder or a little recess
cut out inside the chamber here at the
mouth of the cartridge
or the bullets and the cartridge meet
not a rim so this is a rimless cartridge
and rimless cartridges typically are
associated with semi-automatics and
submachine guns
I really reiterate by virtue of the fact
that they find their position right in
the actual firing chamber and Barrel
which are integral on a small step not
by being held at The Rim
semi-automatics
have two general formats that we might
see besides the mechanism we may have
single action or double action design
but at this point I've got the slide
locked back and you can see the barrel
but in the normal shooting position the
barrel is concealed
inside the slide this piece here
there are some semi-automatics that if
you have astute Witnesses and you're
interviewing them may have noticed a
distinction here in this Beretta pistol
here's the barrel and we can see that
when the slide is closed we can still
see the barrel so it's an exposed Barrel
other examples would be the the classic
German Luger and the Walther P-38 which
have exposed barrels everything I've
told you is insofar as those two
distinctions can also be seen in 22
semi-automatic pistols so even if it's
not a witness if we've got a bank camera
something like that where we can improve
the image on the video camera we might
be able to see some features of these
guns that would allow us to say that the
hold up man was carrying either a gun of
this type or of the colt
um
semi-automatic
now we've got the cartridges being held
in the gun by one of basically two ways
a rim and a revolver on the neck or
mouth of the cartridge in a
semi-automatic
marks being left as those cartridges are
loaded into the gun by really several
sources the first one being the magazine
itself here's a magazine out of that
government coal 45 automatic these lips
on the magazine are preventing this
cartridge from Simply flying out toward
you as a viewer that slide as it came
back and now goes forward will catch the
back of this cartridge just as my thumb
is
and instead of plopping it out on the
floor it's going to of course navigate
its way up into the Chamber of the gun
into the barrel I just held up a moment
ago but in so doing there may be two
drag marks cut into the cartridge Case
by the lips of this magazine
particularly if it's not well made or
well finished that doesn't say the
cartridge was fired in that particular
gun in fact it's an expression or a
statement of the magazine it came from
but it could be and has been used to say
or identify or establish that the
cartridges found at the scene were
stripped from this particular magazine
if we can identify those marks now as
this cartridge
goes into battery as the armor would say
like that
there's a breech block that's pushing
against it
there is an extractor that has come up
over snapped into this groove
that stands to leave several marks as it
impacts the rim goes up and over and
snaps down into the groove
we stand to have three marks made by one
piece of metal they ex the extractor at
that point
when this fires we have a firing pin
that imprints its image into that Center
fire primer that we talked about
we now have pressures going up in the
area of 30 000 even 40 000 pounds per
square inch in some handguns
and of course more in a rifle
that's thrusting that cartridge back
against the breech face of the gun the
tool marks the finishing
features on the breach face of the
responsible gun
are going to print their image right in
the primer and in often in the head of
the cartridge where the written
information is we saw earlier so now
we've got pressures up in the thirty
thousand pounds per square inch the
bullet has now moved perhaps an inch or
so up the barrel this transference of
information is taking place between
firing pin and breech face we've already
got some earlier tool marks on the
cartridge case now the cartridge is
either basically blown out of the
chamber in a simple blowback design or
it's pulled out of the chamber in a
locked breech design such as we're
looking at here in either regard there's
going to come a point where the ejector
the small piece of metal strikes that
cartridge in most guns it's going to be
down around the seven or eight o'clock
position from your Viewpoint strike it
and knock that empty cartridge out and
off to the shooter's right sometimes
upward sometimes also rearward
but it must come out and be cleared of
the mechanism through this area the
ejection Port so imagine in your mind's
eye a live cartridge in this gun a
Hammer's cocked this gun fires in a
single action mode
firing pin just struck the primer tool
marks pressures go up new tool marks
slides starts moving rear rearward and
in this gun which is a locked breech
design notice as I push this back that
what you can see of the barrel and the
slide moved together for a short
distance
now the barrel through a linking
mechanism is pulled down literally
jerked down
if that firing pin is still sticking
slightly into the fired primer there
will now be a scrape mark much like the
break open shotgun I showed you earlier
there's also already been this
transference of tool marks I covered
that
the slide continues back by the thrust
given to it by the discharge of the
cartridge and The Recoil of this
mechanism it'll finally come to a point
where that fired cartridge
is struck by that ejector a small piece
of metal
and knocked out again toward you the
viewer
firearm will reciprocate
it's already recocked itself and load
another round in the battery if indeed
there's ammunition in the magazine
now what happens to the bullet
it's being pushed up the barrel by uh
human sense of things tremendous
pressures
and in that Barrel have to be machined a
certain
number of spiral grooves and a certain
rate of rotation or twist as it's called
the illustration I now have simply shows
us a stylized view looking down a gun
barrel of a gun that has six lands and
grooves the public would normally call
them riflings the lands in this
illustration are white and the grooves
are red grooves are just what the name
suggests they're grooves that are either
cut by a scrape cutter method or a
brooch or they can be formed into a gun
barrel by a forging process or a
swedishing process time doesn't allow to
go in all the methods of rifling but the
important thing is there's great variety
out there in rifling
numbers of riflings and of course we
have two choices of direction of twist
you're now looking at a right twist
well how do we Define that well note
at the top of any Barrel you're looking
down
and imagine yourself journeying down
that Barrel it's not the Twilight Zone
but notice whether in your mind's eye
you're rolling off to the right if you
are it's a right hand twist and if in
your mental Journey down that gun barrel
you roll off toward the left as thinking
about the top up at 12 o'clock and it's
a left hand twist why they didn't name
it clockwise and counterclockwise I'm
sorry I don't know the answer to that
but keep this in your thoughts for just
a moment we'll go to a left twist with
the same number of lands and grooves
of course you've probably figured out
I've simply turned the slide around
but this will give you the idea now does
it matter which end of a gun barrel we
look down well it's not as easy to do on
a video camera but I can show you one
way to prove to yourself it doesn't
matter
this simple little straw has a left
twist if you're looking at one of the
land Impressions or grooves we can call
it either one for that matter in red
and as it goes away from you that's off
to the left
I'm going to take this straw
turn it over you still get the same
answer so been many arguments about this
but it doesn't matter if you look down
the business end of a barrel of a gun to
figure out the landings and grooves and
more importantly the direction of twist
or if you have a way of looking through
the breach in well you think well why
not always look through the safe end
well obviously we're going to make sure
the gun is unloaded but for example with
this revolver if I'm going to out in the
field or in the laboratory
count the number of lands and grooves
and Direction twist I can't look at it
from this direction I've got to look at
it this way and this can be done at
crime scenes and I have trained officers
who are interested in doing this and
they're quite capable of doing it it's a
judgment an evaluation with the human
eye can simply backlight
the bore with just your thumbnail or a
small piece of paper
and I can determine this is six six left
just that quick it's also clean
in other words it hasn't been fired
since last cleaning
with barrels that can be removed or If
This Were A
rifle instead of a shotgun since
shotguns are Smooth Bore fine then I can
simply open the gun up remove the
cartridge and look through this way but
the key thing is direction of twist
determination doesn't matter next trick
is counting and there's one other aspect
of lands and grooves that's of value
in this seemingly technical drawing
manufacturers have a choice of how many
grooves they cut in a gun barrel they
could cut as little as suppose they
could cut as little as one
but in actuality a minimum of two have
been used and in fact a very famous
rifle Springfield rifle in the first
World War
I could cut three some Civil War rifles
had three lands and grooves but more
commonly four five six fairly uncommon
seven very common eight and then some on
up to as many as 22 lands and grooves
and micro Groove systems but in this
illustration you can see that if you cut
a groove or two What's Left Behind is
the land is the raised area or the
rifling if you wish to call it that if
you cut a Groove very very wide
then the remaining land will be very
very narrow
if you cut a Groove very narrow the
remaining lands will be quite wide
so now we have quite a perfusion of
choices here direction to twist we just
got two but the number as little as two
as many as 22. how wide they are or how
narrow is that well I hesitate to say
whim but at the choice of the
manufacturer the engineers
all of that is expressed on the fired
bullet and all of that is useful for
setting
the choices as to what kind of firearm
could have fired this bullet these are
often called a no gun case the FBI
laboratory and most criminalists myself
included have a complete listing of all
the known rifling characteristics by
caliber direction of twist number and
the dimensions
so in such a situation if you have a
recovered bullet and no gun yet the
criminalist or Firearms examiner from
examining the number the direction of
twist and the widths of these lands and
grooves can compile you a list of the
guns that could have fired that bullet
sometimes the list is fairly lengthy if
it were 10 right for I'm sorry six right
for example in 22 very common but if it
were seven right in 380 automatic
present time there's only one gun in the
world that's ever been rifled that way
so that would be a real coup of your
laboratory to tell you and send you a
picture of the very gun you're looking
for and have the detectives or field
officers recover it later
this illustration simply again is a
diagrammatic illustration of our choices
of right or left twist and number of
lands and grooves we've got a four right
at the top left a five right six right
and going across the bottom the only
left twist gun in here six left
they might parenthetically add that that
has been a popular system of coal it's
not unique to coal but with rare
exception cold is always used six left
in their rifling the five right the
upper middle has traditionally been used
by Smith and Wesson and with very rare
exception if someone's re-barrel to
Smith perhaps there'll be something else
but how would you use that information
two officers in a officer-involved
shooting one's got a Smith one's got a
Colt the bullets are mutilated by
hitting brick walls and cars and things
Beyond identification capabilities and
if you settle for a laboratory answer
that says the bullets are unsuitable for
identification you're not communicating
well and you're not thinking both of you
are not communicating well because the
question or matter should be well if
one's got X and one's got y one's got a
Smith one's got a cold can you at least
tell us the general rifling
characteristics on the bullet or bullet
fragments if we can only tell twist the
direction of twist on the bullet
fragments we've still got that one
solved very easily just on that
let's look at sort of the real world
I've given you a couple of drawings this
is a cutaway of an actual Gun Barrel
and we can look down in there hopefully
and see one of the riflings one of the
lands or grooves and on each side of
that the counterpart
you can also see a lot of rough tool
marks left in there from the rotary
reaming that was carried out to make
this gun barrel
it is those features the rough marks
caused by the manufacturing process the
galling of metal chip formation and then
later use abuse normal wear shooting
bullets through the barrel that are
dusty or dirty that give that Barrel its
unique characteristics that basically
hesitate to use the word fingerprint but
that's been popularized fingerprint that
bullet back to that gun as long as we
can find corresponding areas that
survive damage
this illustration tells us or shows how
to determine direction to twist on the
bullets now I talked about the barrels
if you imagine again in your mind's eye
you've got a barrel that's transparent
go back to that instruction I gave you
of concerning yourself with the top
portion of the barrel as you look into
it
imagine now you're above that Barrel or
above that soda straw I used a moment
ago looking through this transparent
Barrel which now has a bullet in it so
that rifling that moved off to the left
for a left-hand twist now leaves a Mark
that does the very same thing and once
again
upper left illustration doesn't matter
whether we point the bullet toward our
belly button or away from us as long as
we look down on the bullet
and ask ourselves as this land or Groove
impression picky the one goes away from
us does it go off toward my left hand or
my right hand
and this one's of course a left hand
twist
again you might think that's all
laboratory stuff but I want you to
understand that every criminalist or
Firearms examiner carries out his
initial examinations many of them simply
with the unaided eye so this is an
acquired skill that many police
investigators have mastered and it
doesn't take a lot of work it merely
amounts to getting a small collection of
bullets of known characteristics to
practice on and why should you be doing
it in the field or be capable of doing
it in the field because you may be
looking for two guns or three guns
instead of one if you see all Full Metal
Jacket at 45 automatic bullets
splattered around a crime scene your
initial visceral reaction is we're
probably dealing with one gun but if you
picked up a couple of those and
discovered that some of them have left
twists Engravings on them and some write
even if you didn't count the number
you've got two guns out there and when a
citizen or somebody comes up with a gun
they found in a trash dumpster it's not
all over it's half over you've still got
another gun if you can't do that at the
scene and if you don't know this already
Criminal Laboratories typically have a
turnaround time of weeks to months
and by now that other dumpster has
emptied and the other gun you're looking
for the one that's probably the Fatal
gun is history
other illustrations that show something
called a revolver skid number four in
this drawing
a fair amount of time talking about how
revolvers are made in this jump that the
bullet has to make from the chamber into
the forcing cone or the beginning of the
Barrel in so doing it very seldom
perfectly aligns with the riflings in
the barrel
in that automatic where I held up that
Chrome plated Barrel from a 45 that
bullet
starts out right up against the riflings
it doesn't have anything to jump across
so it's going to be perfectly aligned
and and engage the rifling true and
straight a revolver bullet or a bullet
fired through a revolver seldom does
around its entire circumference and a
careful Discerning Eye with a hand
magnifier sometimes just visually can
pick up what's often referred to as a
revolver skid this is a momentary
gripping of the bullet engagement of the
riflings and then a re-centering as it
sort of settles in and moves another
quarter inch or so up the barrel and a
re-tracking sort of like backing your
car up in the snow and then moving
forward again to make a slight doublet
of a track a characteristic of a
revolver there's also some
characteristics about the bullets that
are used in revolvers I've talked about
combining those two if I were at one of
your scenes and picked up such a bullet
I probably word it this way the
likelihood is
given this revolver skid or these skid
marks and a lead canelord bullet we're
looking for a revolver very unlikely
that we're looking for a semi-automatic
and people beating the bushes looking
for an ejected cartridge casing are
probably wasting their time
now there's something else we can do at
a scene that's field expedient and very
easy if we've got different types of
ammunition and we've seen a great
variety of ammunition in the same
caliber and cartridge designation
involved in a case we could have one gun
shooting multiple types of projectiles
we can do a Base to Base comparison by
very carefully
juxtaposing two recovered bullets and
seeing if we can phase them if we can
line up the land and groove impressions
that's also shown in an illustration but
if you recall it doesn't matter whether
we look at it front to back or back to
front if indeed we have one firearm one
gun involved we will be able to phase
the land and groove Impressions both in
their direction of twist and in their
spatial relationship their widths in
other words it'll look like a Continuum
engrave the marks across these two
bullets on the other hand we could
either have people sharing ammunition
with two different guns or combine them
both different ammunition two different
guns in the same caliber a Colt 45
automatic and a Sig 45 automatic or some
similar Arrangement the Beretta and a
Smith and Wesson and there this sort of
Base to Base comparison just carefully
bringing the two bullets near not
grinding them into each other would
quickly reveal a difference in land and
groove count we wouldn't even have to
count them we'd simply see that we can't
phase the two that we've got some sort
of mismatch here and once again the
importance is the investigator right
there that night is alerted that he has
at least two guns in this last situation
here's some actual bullets we've looked
at drawings but actual bullets enlarged
where we can look at this kind of
comparison
on the left we've got
two they happen to be Federal brand a
357 magnum bullets we've seen several
times before
a Base to Base both of these were fired
either from the same gun or from a gun
with the same general rifling
characteristics which weighs the twist
it's a right twist
the two in the middle have substantially
more lands and grooves there's
as I recall 12 in this particular gun
this does happen to be because I fired
them the very same gun but two very
different bullets a silver tip round by
Winchester on the top
and 147 grain subsonic bullet below but
we can phase them just as we did the two
on the left now here's a mismatch on the
far right we've got a Winchester
jacketed hollow point bullet above
that started to expand but more
importantly it's a left hand twist take
a look at it the rifling Engravings go
off to your left whereas the lead three
cantalured bullet down below has very
wide land and groove Impressions
distinction number one and secondly
they're off to the right so we have a
left twist and a right twist gun we've
got to have two guns and of course two
different types of ammunition even
though they're both 38 caliber or 357
Magnum caliber and I think the last
example I'll give you is how subtle uh
rifling Engravings can be with one new
type of product on the market called the
polygonal rifling system this is being
used by the West Germans now just the
Germans I suppose Heckler and cook for
example
and Glock the particular bullet on the
right
was fired from an Heckler and Coke nine
millimeter
the type of bullets full metal jacketed
uncannelord are the same in both of
these
but there are virtually no discernible
rifling Engravings on the bullet from
the polygonal rifling system that in
itself becomes a nearly unique
characteristic
the one on the left has clear land and
groove Impressions and again this is a
quiz right or left twist
right twist
firing pin Impressions I've talked again
about the firing pin leaving some marks
and Rimfire cartridges and the examples
in the upper row we've got everything
from flat round firing pin Impressions
to hemispherical
to square to rectangular and even some I
haven't shown you earlier I believe I
gave you a triangular one
those are all characteristic of the
company that made the gun and they will
usually be consistent for a particular
make and model for year after year so
that can become a useful characteristic
in compiling you a list of possible guns
that fired a cartridge before we ever
have the gun
the shapes of the firing pins are shown
in the lower figure gives you simply a
profile view so you've got some idea of
how these things are going to leave an
imprint whether it's a Rimfire cartridge
or a center fire cartridge
the breach faces of the guns that that
hold these cartridges in place whether
it's a rifle a pistol or a shotgun and
the marks that transfer during firing
and the next item of Interest I've shown
you here in this illustration three
different styles of breech face
design or finishing the upper one that
I'd simply have called a Colt type
we have a gun like that here
and that has been finished by the
manufacturer
simply by going in here with a milling
machine
and milling and finishing the surface of
that breech face with a vertical Milling
or filing tool what that of course
leaves on this flat breech face is just
that tool marks faint vestiges of an
array of tool marks that go from top to
bottom
on the other hand certain other guns
like a Luger or a P-38 both from the
second world war and nine millimeter
have the breech face recess where a tool
has gone in there with rotary motion and
cut out metal so we could and there are
have guns all in nine millimeter all
shooting the very same brand and loading
of ammunition
but because one has a recessed breech
face the only way you can do that is
with a rotary Milling tool that will
print circular tool marks in the primer
of the fired cartridge
the Colt type design is going to leave
parallel tool marks on these fired nine
millimeter cartridges and finally we
have where the extractor and ejector are
located in these three guns that also
will leave a little gouge in the rim
where the extractor rides over we'll
leave a little ding Mark in the
cartridge case where the ejector strikes
it
and I reiterate this is something that
is not heavy science it's simply
observational and it's a skill that one
can do and many investigators do do
right in the field so in this
illustration I've given you the style of
the breach faces of these three guns and
what the cartridges from them would look
like so a quick example will go on three
nine millimeter cartridges by federal
one of them has circular tool marks
imprinted in the primer and the other
two have parallel or vertical I'm not
prepared to say we're looking for a colt
and a Luger at that point but we're
definitely looking for two guns just on
the basis of a fired cartridge even if
the bullets are never found
okay now let's summarize pull together
here all the kinds of marks that can be
on a cartridge because I have left out a
couple
we've got the firing pin impression I've
talked about that a firing pin scrape
mark only for those guns that have a
locked breach that are pulled apart by a
linking mechanism such as the Colt
Browning design
we have the tool marks from the breech
face that are printed right in the
primer and sometimes in other parts of
the head of the cartridge the extractor
gouge and override the ejector Mark was
semi-automatics that knocked the
cartridges clear I should point out
extractors and ejectors of course are
not present in a revolver
with simple blowback design guns an
example would be this little Walther
if you go back and look at the coal I
Illustrated to you the barrel and slide
move rearward together for a short
distance and then pull apart this gun
the barrel stays in place and the slide
simply goes straight back in other words
the powder gases are pushing the bullet
this way and at that same instant
they're already pushing the slide that
way that's called a simple blowback
design that raises some new phenomena
phenomena
that cartridge case in a blowback design
gun is blown out against the chamber
walls and it's also starting to move
in the locked breech design the delayed
unlocking system the cartridge blows out
against the chamber walls but in the
next few milliseconds relaxes and this
is before the action starts opening up
in other words before the cartridge gets
pulled out of the chamber so what I will
typically see in cartridges from
straight blowback guns
are chamber marks scuff marks on the
cartridge itself again if you're a
shooter pick up some 380 sometime and
look at them you'll usually see scuffed
marks on the cartridge 22 autoloaders
are all straight blowback design
cartridges from those will typically
have a slight scuffing on the on the
wall of the cartridge pick up a 380 from
a locked breach a 380 and there are a
few of them out there the Llama is one
example you'll seldom see that so those
are ones I I failed to mention earlier
chamber striations and finally one
that's not even in this illustration but
I have a couple here too
to describe
in the extraction and ejection from
cartridges from semi-automatics and for
that matter full automatics quite often
the cartridge will come
careening out of the action or tumbling
out of the action and strike some
portion of the ejection port
now what's an ejection port
that was this area here for example on
this 45 automatic they'll either strike
something back in here this portion
or even up here along the side wherever
it happens it on occasion happens with
consistency
and it will leave a nice deep crease or
indentation such as we can see on this
cartridge
that again tells me I'm dealing with a
semi-automatic gun as opposed to a bolt
action or a lever action or a pump
action you simply can't operate those
mechanisms fast enough to create this
kind of damage
these particular cartridges I'm holding
up are unique in another way they're a
certain number of guns not many a few by
Heckler and Coke and some made by the
Soviets in the second world war that
have fluted Chambers there are grooves
cut in the chambers of the guns and this
is to help break the cartridge free of
the chamber
but what they do is leave little
indentations or Scorch marks along the
casing once again the sort of thing that
the astute investigator might observe
certainly I would hope the laboratory
would note and if we didn't have a gun
yet that tells us much about what we can
eliminate and how narrow our search can
be restricted to in trying to find the
gun that in this case fired these 5.56
millimeter cartridges and there are a
lot of firearms chambered for this round
but right now there's only one I know of
that has a fluted chamber
at this time there's only one rifle made
by Agent K that's so chambered with a
fluted chamber in 5.56 millimeter there
are others in other calibers that again
are tip-offs to the kind of gun we're
looking for right we've looked at the
various marks left on cartridges and how
they can be used to identify the
responsible gun as well as tell us
something about it I thought I'd just
take one very brief moment to use this
this training tool this court exhibit
for how the actual identification on a
bullet is made and this enlarged model
of a bullet has a rifling engraving a
land impression here
here
and over here and in the microscope
that's used in the laboratory we can put
a test-fired bullet on one stage and the
evidence bullet on another and see them
through a split field where we can
juxtapose them optically and all of it
is done is after the bullets are phased
after they're brought into alignment
such as you see here simply rotate one
of the two bullets your choice until we
find sufficient correspondence in the
fine striations the tool marks that are
left by the imperfections in the barrel
of the gun and I've said several times
now this doesn't always work and that's
because we've got a number of things
that can occur damage to the bullet can
be substantial it obliterate the
information or we can have a gun that
just doesn't reproduce marks very well
it's leaving leading in the barrel with
each shot or the bullets basically
wobble down the bore and it just simply
doesn't leave reproducible marks but
that we can determine by test firing so
in summary a trained skilled examiner if
he can find or she can find sufficient
correspondence in the individual
characteristics they'll fall in
alignment with one another they'll
represent a Continuum not only in the
rifling Engravings but in these
striations
let's look at a very different type of
ammunition shotgun ammunition
the illustration the drawn illustration
presently shown we can see some very
different features first of all we don't
see a projectile or a bullet
and we see a cartridge that's not made
of metal of steel or brass but rather
largely paper or plastic
in this country most are now plastic in
other parts of the world the cartridge
this area in green is paper
the bottom of the cartridge or head as
it's more properly called will be some
sort of metal either brass or steel
inside of which will be some sort of
propellant one of the kinds we've
previously seen usually a flake powder
of some kind disc flake or the lamels
or ball powder there is again a
centrally located primer so it's a
center fire type cartridge with the same
sort of composition at least in American
ammunition as we saw earlier
but above that powder charge can be
several types of waddings now this
illustration shows you Contemporary
American ammunition that have plastic
wads or shot cups these hold shot small
lead alloyed pellets they may also be
copper they may also be steel but
generally and more commonly at least
traditionally they are lead and their
size can vary considerably and of course
given that the number that we can put
inside of one of these shells can vary
let's go back to the wads these wads can
take on a great variety of forms some of
them are quite intriguing in the
geometry that companies have put in
there and these are all patented
processes so the wad has to
carry and push the shot out of the
Smooth Bore of a shotgun no riflings in
there
it has to protect the shot from rubbing
against the inside of the bore so it
basically cradles or cups it in the
versions you're now looking at
and then once clear the barrel the wad
like a booster rocket simply Falls away
it has some ballistic characteristics of
it own its own but it doesn't go very
far
but also since it has to fit the bore
tells us something about the gauge which
is the nomenclature used to describe the
size of the bore the diameter of the
bore in a shotgun and commonly there's
12 gauge 16 gauge 20 gauge and although
it's somewhat of a misnomer 410 gauge
that's really a caliber it's 0.410
diameter
so 12 gauge they go just in reverse the
small number means it's bigger a 12
gauge is about a 73 caliber 0.73 inches
across
and here for example is a 12 gauge
shotgun shell it's plastic this
particular one is made by Winchester and
we can see some written information on
here this is also diagnostic we're going
to have three entries on most American
shotgun shells the three and a quarter
it's called the dram equivalent it's an
archaic term that was carried over from
black powder days at the turn of the
century that related to the amount of
powder smokeless powder now that you
have to put in this shell to be
equivalent to in this case three and one
quarter dram of black gunpowder it's
really an expression of the Velocity
ultimately
the one in the middle here tells me that
there's one ounce of pellets of shot
inside this shell and finally the number
eight tells me something about the size
of these pellets and if we were to
disassemble this shell that can be
easily done with a scalpel or razor
blade simply cut open this cartridge and
make a window available we could look at
the wadding in there and how it's
arranged
you can also see if there's great
Variety in in color and writing on these
shells how much of this brass base
exists this one on your right is a paper
shell the other two are plastic
so again much variety and that's great
from a forensic or criminalistic
standpoint if all shotgun shells were
the same finding them at a scene other
than than basically saying a shotgun was
used wouldn't be very exciting
these wads have other ballistic
characteristics they emerge from the
barrel of the gun basically with the
same velocity of the shot they will have
imprints of the shot that They Carried
that are forced in there by the sudden
accelerated forces they'll have powder
residues on their base that we may be
able to compare with a kind of
propellant in the Shell or in the barrel
of the gun
now you've seen how briefly how bullets
are identified one of the troubling
things for us all about shotguns is we
cannot match the pellets the BBS the
shot to the gun that fired it and that
should make sense now because if it's in
there cushioned and protected from ever
rubbing the barrel it's hopeless even in
older shells that have fibrous wads that
we'll see in a moment where the shot
does rub the barrel the ability to
reproduce that event to find another BB
that rubbed the Barrel in just the same
way is basically a lost cause and not
done but the wads on the other hand
especially the plastic ones that were in
this illustration if they rub across a
rough Barrel a sawed-off shotgun for
example that hasn't been
re-crowned or re-finished at the muzzle
there in those instances we can't okay
on occasion match the wad back to the
shotgun that fired it but that's a
pretty rare event
couple of illustrations from the
manufacturers and these sort of
brochures are handy things to get if you
are involved in Firearms cases and want
to keep abreast of the field this
particular illustration helps us in two
respects it shows us the range of size
of shot that's available this is from
Remington's advertisement and the shot
in shotgun shells can be as small as
number nine which measures out .08
inches in diameter
it can be as large as triple lot Buck
which is basically the size of some some
pistol bullets .36 caliber or 36 caliber
bird shot or normal shot goes up through
BB size and that one at the end of our
charts about 0.18 inches
Buckshot is available in a number of
sizes but commonly four and double ought
are the ones that we'll encounter most
often because they're popularly used in
law enforcement and occasionally in in
the eastern part of the United States
for hunting in populated areas because
their range is very limited and as the
name suggests Buckshot it was originally
intended for hunting deer
this illustration also shows us
something else some of the Remington
plastic wads now exposed to the windows
cut in these shelves and variations in
the design of those wads it also shows
us BBS are shot that are copper plated
just like that lubeloy coating on the
Winchester 22 bullets here we've got a
situation where lead shot has now got a
copper plating on it
and on the far right normal chilled shot
or lead shot and finally there's
something else that should be visible
here although subtle a white powdery
plastic material this is a polyethylene
or polypropylene buffering material
sometimes called grex grex in the
industry it's in there to cushion the
shot so when they are accelerated
forward during firing in those thousands
tens of thousands of pounds of pressure
I described earlier they're not deformed
as badly as they otherwise would be that
has ballistic characteristics at close
range it's like terminal dandruff it's
all over the victim and the scene
at close range it follows the shot and
the wad right on in so while we're
robbed of the opportunity to match the
projectiles the shot with the
responsible gun we've got a lot of other
things we can deal with from a
reconstruction standpoint
here's another Remington entry that has
occurred in the last five or six years
steel shot because of the concern with
lead and the environment virtually all
the manufacturers in this country also
offer steel shot
Remington's gone one further and as now
I believe as of other countries
companies excuse me and that is to put
two different sizes a shot in the same
shell ten years ago if you'd brought me
pellets from a body that were two
different sizes I'd say the person's
been shot at twice and hits were scored
both times with two different sizes a
shot they mean two guns Just or just two
shots now we've got a situation where we
can find Two Shot sizes of shot with a
single blast or discharge
here's some actual fired wads from case
work years ago that will give you some
feeling for the great Variety in these
wads with one exception there is one
that's unfired the one on your left
that's a sort of creamy white that's an
unfired plastic shot cup there's a shot
shell there with that same sort of
nomenclature the three-digit entry that
I described but now we've got a fired
Remington power piston how do I know
that by the sort of figure eight
features in the bottom of the shot cup
or plastic wad
we've got some that are just fibrous
wads a more old-fashioned or traditional
style or three of those indicated here
's an over powder Wad and the wad that's
immediately next to the powder that's
plastic and then some sort of strange
looking things that look like discolored
strips of plasticized paper or simply
just strips of plastic that have all
sorts of little dimples and indents in
them that's a little collar that's put
in most Winchester shotgun shells and it
also as do all of these things except
the shell go out the muzzle of the gun
upon discharge and they have ballistic
characteristics and features of their
own that tell us something about the
gauge the brand of the ammunition and
given their ballistic characteristics
which is determinable something about
the distance between the gun and where
the shot went in other words we can use
that to determine where the shooter was
and how far away he was if these things
are located and first of all we got to
know what we're looking for finding a
little
squiggly piece of plastic like this shot
collar is evidence and not just some
remnant or something from a chewing gum
package
here's another Remington shell from an
actual case years ago that became very
interesting just because of the
difference
in these entries one says two and a
quarter one says two and a half gram
equivalent one of them is virtually
unobtainable anymore it's so rare and
that happens to be what the subject was
using even though he got rid of the gun
he had ammunition of this type in his
possession and and fired round of that
type was at the scene and that became
extremely important in that particular
case another Remington power piston is
shown just above that
here's a contemporary Buckshot load in
12 gauge this happens to be a Winchester
shell a Super X on the side of it which
is one of their brand descriptors and
we've got two
fibrous or cardboard Wads in this shell
that are basically the the caliber or
the gauge of the gun
we have a bunch of this grex material
this white polypropylene and I've
removed several of the pellets with
Buckshot there will be a discrete number
of pellets per shell with the very small
shot there'll be a range if you put an
ounce of very very small pellets in a
shell you may have 270 in one and 275 in
the other but with Buckshot there'll be
a discrete number and that again can be
useful because the same company
may make you three loadings in in the
same size of Buckshot and that's what
I've shown you in this example at the
top is a three inch 12 gauge
Remington Buckshot shell it has 15
pellets in it
and if you start following through with
me and look at the wads that are in this
particular shell there's a green plastic
over powder wad the one right next to
the powder
and then a filler wad above that of
cardboard or fibrous material look at
the dimensions they're different
thicknesses or lengths depending on how
many pellets were in this shell the one
in the middle is a two and three quarter
inch long shell still 12 gauge still
made by Remington and it was loaded with
12 pellets
and finally we've got one that's again a
two and three quarter inch shell
with nine pellets the more common
version well you'd again think well just
count the pellets in the body well we
may only have a hit with three out of
nine or three out of 15 pellets but if
we can find the wads between the victim
and where those wads are located we now
have an extrapolation line to go back
and look for the shooter's position and
once we locate where those wads are and
know their ballistic characteristics we
can say how far back along that line the
shooter was
and that given the type of Wads were it
was a 15 pellet load or a 12 pellet load
and if we can find the spent round that
sort of information may be labeled or
determinable determinable from the
cartridge itself
so there's an interrelationship between
these class characteristics as they're
called
the range of shotguns I mentioned that
the pellets
because they disperse from the gun obey
certain physical and mathematical
principles they're basically radiating
out from a central point coning out over
distance and basically they obey a
straight line if we look at the upper
graph of range or distance versus
pattern diameter in other words what
sort of a circle would all of those
pellets whether they be small shot or
Buckshot what sort of a circle would
they fit in while at contact I imagine
it's not hard to Envision that if this
gun the shotgun of nominally 0.73 inches
is right up against me I'm going to
basically have a three-quarter inch hole
with all the pellets and all the powder
that's not burned and the wads going
right on in if we start getting a
separation distance now we've got wads
that are falling away from the shot
charge and leaving injuries of their own
they may be sticking in my coat or my
skin we still may have a massive shot
that's basically going in the body but
there'll come a point where we start
getting satellite pellets
around the injury site and finally we'll
just have a pattern of pellets that
basically will fit inside a circle if
the shot is delivered at a 90 degree
angle to the surface and that's what I'm
illustrating in the lower picture trying
to summarize muzzle of the gun gunshot
residues that we've already talked about
a Fanning out or a coning out of the
shot shown over here at the far right
and a diameter of that pattern based on
distance and somewhere in between a
substantial range such as 20 yards or 50
yards those wads are going to fall to
the ground and they're out there
somewhere and they'll typically be in
the same area for that particular gun
and ammunition combination
this group of dots that's being
projected is a useful way to learn
something else about shotgun blast this
is a reconstruction of an actual pattern
of number four Buckshot a 27 pellet load
of buckshot
and I can use this and and
demonstrations such as this to show you
what happens when we either shoot at an
angle or shoot against things that
aren't nice flat pieces of paper and if
I simply start moving
forward
now we're going to have some strikes
that look like they're grazing shots
across my body others that are going
basically straight in from your
Viewpoint or if I lean away
now we have an ellipse
well there's a mathematical relationship
of the major diameter to the minimum
diameter in an ellipse with a little
pocket calculator
if you use the sine or cosine function
I can tell you the approximate angle
that a blast of shot came into a surface
from by the size the dimensions of that
ellipse
likewise if we make the foolish mistake
of taking my jacket from the medical
examiner's office and laying it out on a
flat table we're going to see some
pellet strikes that are coming in at a
grazing angle the ones that were coming
across my forward torso and others that
are going straight into the jacket
leaving nice round holes and if you
don't have this concept in mind you
could make some erroneous conclusions
that we basically got more than one shot
grazing shots and straight in shots no
you've got a pattern of shot that was
inside of a circle that's hitting a
cylinder basically a cylindrical object
so this sort of information and
understanding about shotgun ammunition
and its ballistic Behavior can be very
useful in reconstructing the crime and
establishing the range as well as the
position of the shooter
this next illustration from one of the
industry Publications shows one of these
plastic wads actually emerging from the
muzzle just a few inches from it the
shot string is still closely aggregated
the petals on this plastic wad are just
starting to open up as they encounter
air resistance think of this like a
badminton birdie in reverse that it's
going to open up encounter wind
resistance
and it's going to do a turnaround
and this drawing from a trial many years
ago I'm illustrating how a similar wad
the Remington power piston opens up
within a few inches of the muzzle and
then because the center of gravity is
aft toward the rear
it naturally will turn around at point
three and four and this will occur again
and again in a very reproducible fashion
with the particular wad
gun combination
it can be used to establish range and
the reason this is useful is that very
short distances shotgun blasts all
produce basically around entry hole all
the pellets are going through one
opening and that could be the case that
10 inches or at 30 inches but the wad
the power piston type wad is going to
behave very differently at those two
distances and so that could be the
difference between a suicide a shotgun
that I'm holding just a few inches from
me and discharging with my extended hand
or reaching up with my toe or a shotgun
that fell off a table hit the floor and
discharge from three feet away the entry
hole from the pellets going to be
indistinguishable in most cases but what
the wad does to that body or to me in
this example is going to be quite
different
and here's an actual autopsy picture
if you look at it carefully we'll see a
number of things first of all here's one
of these types of Wads this one doesn't
have to be Remington so I don't mean to
be picking on any one company they all
behave basically the same way here the
pedals we can see on it and this is an
entry wound a rather serious one in a
man's head
and we can see two red rectangular slap
marks
and that's where two of the four Petals
of that wad basically slapped against
the living skin
and left a an abrasion an image of
themselves there are even some little
satellite punctate Marks here that's the
powder the powder particles that are
coming out in miniature shotgun blast
fashion and also telling us that the
range is close so we could actually do
test firings as long as we've got the
gun and more of the same ammunition
and establish it what distance do we see
this is it 10 inches one foot or is it
two and three feet could be again the
difference between a homicide and a
suicide
it's another type of what I mentioned in
brief but also gives us some interesting
phenomena from a ballistic standpoint
this particular Winchester round that I
held up earlier has this plastic shot
collar that you saw after firing this is
what it looks like before firing that's
curled or rolled around inside the shell
to protect the shot from scraping the
bore the inside of the barrel of the gun
there are three other wads cardboard or
fibrous wads here you might notice one
of them has actually taken up the image
of the pellets that it fired so I could
determine the size of shot from such an
imprint in a wad and I have the gauge
from the size of that wad and finally
from this little shot collar we're back
into a situation where we might be able
to resolve one foot versus two or three
feet if you imagine this little curled
piece being fired out of a gun it's
certainly not going to carry very far
it's just flapping around in the in the
relative wind and the breeze that it's
encountered by being discharged and it
indeed does so a very quick quickly this
from a Winchester publication shows the
emergence of shot with these three wads
and the shot collar and at nine inches
it's basically still wrapped around the
shot as we get out to about 18 inches
the wads are starting to fall away and
this collar is starting to unfurl and
the last lower picture it's basically
unfurled out around two feet or so
this is an actual case that was sent to
me for other reasons and one of the
issues was that this man who who shot
his estranged wife had done so from some
considerable distance 10 15 feet away
this is the entry wound in this black
and white photograph and right away
without even firing the gun I can tell
you that was a lot closer than 10 or 15
feet but notice this little injury in
the skin over here to the eight o'clock
position
that's that collar that plastic collar
still flying edgewise
with you know sort of a crescent shape
with enough energy to actually break the
skin
so we once again have a situation we can
control the variables we've got the gun
more of the same ammunition important to
seize more of the very same if it's at
all possible or put it on a search
warrant to be secured and test fire the
gun against suitable test media such as
those described by Dr fackler skin
tissue stimulants from freshly
sacrificed pigs so on to establish where
do we see this kind of phenomena and is
it reproducible and consistent
now lead shot is not necessarily unique
to shotgun shells there's some products
that contain it in bulleted ammunition
and this is an example that's been
popularly promoted the particular one I
have here is a Glazer nine millimeter
Parabellum cartridge it's also available
in a number of other calibers but it's
constructed in a rather interesting
fashion we have a copper jacket much
like many of the other bullets we've
seen
inside of which is not a Lead Core but a
large number of very small lead shot
capped by a blue nylon ball all of these
things of course emerge from The Gun
Barrel when they enter the target
the jacketing expands or breaks away
usually into many fragments releasing
the shot into the injury side or Target
should be noted that that blue nylon
ball doesn't show up on x-ray so some
Clues to the pathologist and surgeon
finding copper jacket fragments and of
course very small lead shot clearly says
we don't have a shotgun yet we've got
shot
a search for the small blue ball would
cinch it that we have this particular
product the Glazer safety slug as it's
been called and then the laboratory can
do its identification work if
the appropriate number of fragments of
the jacket are found that bore against
the barrel of the gun the riflings there
are other shot cartridges available
here's a shot cartridge even in 22 rim
fire about the smallest you can get that
could be shot in n22 revolver or
semi-automatic pistol if you can get it
loaded into the gun easily
and of course the rifle I showed you
earlier any 22 rifle designed for Pest
Control shooting rats and mice in the
barn without destroying the barn but
they've been shot at people also
here's a 357 Magnum cartridge with this
yellow plastic cap on it inside of which
is a number of as I recall number 12
shot might be as large as number nine
that's easy to determine we'll just
disassemble one this plastic Cartouche
cartridge around it also over short
distance has ballistic characteristics
of its own just like the wads and could
be used along with the pattern of shot
to establish range so long as we get
more of these and we've got the gun
earlier I held up a nice government 45
automatic
this pistol here here's a cartridge
that's been designed with even a step in
it and a and a crimp so it will
negotiate out of the magazine up through
the feed ramp and into battery and even
work the mechanism of this pistol this
particular one's made by Omar or CCI and
it's loaded not with a bullet but was
shot
of course the number of pellets in the
size are going to be greatly reduced
over a shotgun shell but I offer those
just so we understand that shot can be
found in some other other formats
here's a slide we've seen earlier with a
mixture of 22 rim fire ammunition with
various types of projectiles loaded in
them the case I'm going to show you is
an example of where an individual is
used such an assortment of ammunition in
a revolver this occasionally happens
there seems to be a certain element out
there that scrounges up ammunition to
use in their firearm and this can be
very useful
in this particular case example we have
a situation where there was a backyard
party that got out of hand one of the
participants assaulted the homeowner the
party Giver the host by breaking a beer
bottle coming toward him so went the
account whereupon the homeowner produced
this revolver that we see here on the
table
a little closer view
so let me stop a moment is there any
reason to fingerprint this gun not
really he owns it he admits holding it
he admits shooting it it's how and why
this shooting took place that's
important not what is the responsible
gun or making a Firearms identification
so as investigating officer approaching
this case we have a person who's
describing a self-defense situation that
the subject got out of hand started
becoming obnoxious broke the bottle came
toward him he armed himself fired a
warning shot into the ground so there's
shot one the subject came closer he
fired a warning shot into the air now we
have two shots and finally when the
subject was virtually on top of him
about to jam the bottle into his throat
he fired whereupon the decedent the now
decedent fell
so we get in a little closer to this gun
after photographing it and documenting
it in place as to what it looks like
then it should be marked with something
like a Sharpie type permanent marker
even white out something that will leave
a mark on each side of the cylinder on
each side of the back strap such as you
see here then and only then can we
carefully open the revolver in this case
and look at the arrangement of
cartridges now I've reproduced the three
types of cartridges that show a firing
pin impression these cartridges are not
taken from the gun they're simply put
here for illustration the fired
cartridges amount to
a Winchester Wildcat that's the stylized
w
the next one a federal that's the letter
F with again a firing pin impression
present in it and finally a cartridge
with the letter U the Remington
cartridge and if we look at those
bullets we can see we've got three
different types of finishes on the
bullet
we later learned that the cylinder in
this revolver rotates counterclockwise
so I've put an arrow on it just for
instructional purposes that would later
be learned at the laboratory the
important thing is you if you're
investigating officer or arriving
officer have marked this cylinder so we
know which cartridge was under the
hammer and that's the one with the
letter u
I'll study this a moment and determine
which would have been fired first second
and third
well clearly the one under the hammer
would be the last shot that's the
Remington cartridge
what if the cylinder had been Advanced
if the subject had elected to [ __ ] the
gun for a potential Force shot and then
decided against it and let the hammer
down then we'd have a situation where
that Remington cartridge the letter U
would be offset one position
if investigators Rush In And clear the
weapon initially all of this information
is going to be lost here we have a
pretty well done documentation of the
evidence so let's go back to the
shooter's account if indeed he's telling
us the truth
then the bullet in the decedent should
be
Remington bullet the last shot what if
in fact autopsy reveals a plain lead
bullet
the Winchester bullet
then we have a person who's mistaken at
best and lying to us at worst because
the first shot the Winchester bullet is
the one in the decedent and the other
two are misses and this account the
story is simply a fabrication
to try to cover up what actually
happened
of course revolvers aren't always used
in in shootings and ammunition isn't
always mixed but this is something
that's important to do in each case and
I'll show you one last example from a
very famous case of how a diagram then
would be the last step in documenting
what we see in a situation like this
this is a center fire revolver wherein
we've got not only fired cartridges and
unfired cartridges but we also have a
misfire and this really doesn't have to
be fancy I've even seen it written on
the back of a breathalyzer test record
card by an officer who had nothing else
to write on at the time so simply a
little diagram that shows how many
chambers are in the cylinder what
cartridges are in those chambers a brief
description of the head stamp we now
know what that is
and then finally after this is all done
these cartridges are going to be removed
now let's talk about marking of the
evidence itself
revolvers such as this we've talked
about already and marking the cylinder
but if we're going to identify this gun
later as the revolver that we found at a
scene or seized from an individual
recovered we need to have not only its
serial number but some mark That's
Unique our initials and a date somewhere
on it
good choices are inside the frame for
example which won't permanently deface
the firearm on the Yoke or crane as long
as one's consistent you'll always be
able to find that Mark at a later
hearing or trial
if it's something that doesn't lend
itself to some common place then make a
note in your report or supplement as to
where you placed your initials some
agencies I should point out do have a
Prohibition against marking firearms and
even ammunition components if that's the
case then a tag suitably affixed
somewhere through the trigger guard with
your again initials date case number if
there is one by then and again the
serial number
serial numbers are trickier than you
might think for example on Smith and
Wesson's the number that appears in this
area isn't necessarily a serial number
it's a frame number and the serial
number is on the butt here we've got a
gun that has the butt covered up with an
enclosing grip
so
there are some potential problems with
trusting to serial number alone with
some old World War II Firearms certain
serial numbers were duplicated on the
same make and model of gun
let's look at a semi-automatic how we
might mark it if we're going to elect to
do so
well this is one we've looked at before
it has a slide which conceals the barrel
and if we don't wish to face the gun
itself
and it may be something that's of value
to be returned to a victim of a burglary
and we also want to Market in such a way
that we're dealing with a component
that's a part of the identification
chain something that contacted the
bulletin cartridge so I wouldn't want to
mark on the grips they can be removed
but here we've got an easy answer once
we've got to the point where we are
going to secure and clear the weapon
it's still in our custody we could mark
it here on the barrel it's normally
concealed by the slide alternatively we
could mark it here on the side of the
chamber with a small pen knife or
something that will scrape in a serial
number our serial number ID number
initials or dates something that we can
identify and say is a Mark we placed
there
let's look at ammunition components
we've seen already where the basic
identifying information is located on a
cartridge
we've got the head stamp area
where the breach face signature firing
pin impression extractor and ejector
marks are located so that's certainly a
prohibited area
we may have chamber marks on the side of
a cartridge or magazine lip marks that I
discussed earlier so we've got to make
some intelligent judgments here some
authors have even recommended I'll use
another cartridge here
putting initials inside the mouth of the
case well that's possible with larger
cartridges but it's virtually impossible
with something as small as a 22 rim fire
so it comes down to making some Judgment
of looking at the cartridge after you've
seized it or impounded it and seeing if
there's a clear area that lacks any
marks that may have been caused by the
firearm that chambered it or fired it
and then so initialing it and again
possibly a date if you wish there's
another philosophy to marking cartridges
and bullets and that is to Simply place
them in a secure container so we could
have taken that cartridge or a bullet
that I'll get to in a moment and put it
in some sort of suitable vial film cans
are great they don't break and they're
pretty sturdy so we could put a place
piece of tissue paper or Kleenex not
cotton inside this vial place the
cartridge or bullet in there another
piece of tissue on top of it so it
doesn't rattle around and dislodge trace
evidence seal it and then thoroughly
tape seal the container initial and date
the container case number perhaps and I
assure you that the criminalists or
Firearms examiner in the laboratory will
be careful to leave your seal
identifiable and your initials cut
through it in a certain area reseal it
so you'll be able to find those marks
and seals at trial
bullets
again we've talked about where the
identifying information is located on
the bearing surface but I've also shown
you powder imprints on the base of the
bullet there may be trace evidence from
Impact or Ricochet other questions so
you once again need to make a judgment
call certainly the bearing surface is
not acceptable the base may be
acceptable if you look at it and see
that there's a pristine area with no
indications of something that might be
of evidentiary value no adhering Powder
particles or imprints then fine the base
is a great place to initial and possibly
date this bullet we could use any area
of the nose of the bullet that doesn't
have any visible trace evidence
the same philosophy however is employed
by some agencies of Simply securing the
item in a container and ceiling and
marking the container and no problem
with that as long as you properly seal
and market and of course the people that
handle it later
note those seals and don't deface them
I've mentioned several times trace
evidence on bullets I'm going to show
you an actual case that hasn't been
completely litigated yet but it's a
great learning exercise this first
picture is a police photograph which I
have re-photographed and noted a bullet
laying on a driveway briefly the
situation in this case is a man shot to
death in front of a house bullet passes
completely through there's a search of
the area of course to locate the bullet
this is a neighborhood where finding
bullets is not uncommon so one of the
one of the important issues in this case
is this bullet that you're now looking
at the Fatal bullet
and of course no gun has been recovered
yet there's a substantial number of
potential Suspects
so something about the gun that fired it
from the rifling characteristics what
brand of bullet what caliber what weight
and of course any adhering trace
evidence that might tell us whether or
not it passed through a human being
to illustrate this I've got the Fatal
bullet or I'm sorry the bullet from the
driveway shown on the upper left we can
see land and groove Impressions they can
be measured and counted and when that's
done we find that it's five right land
widths equal to the grooves it's 38
slash 357 caliber a fairly short list of
guns it could could fire this 357 Magnum
bullet are available and they basically
amount to Ruger certain rugers and Smith
Wesson's chambered in 357 Magnum this
bullet is not available in 38 Special
so we've got a fairly narrow range of
guns that could have fired it you can
also see some pretty substantial damage
to this bullet two areas of impact up
near the nose toward the top of that
bullet's view below it
is a cartridge case a Winchester 357
Magnum cartridge case that seized from
one of the suspects homes no gun is
found but a cartridge case made by the
same company in the same
cartridge designation 357 Magnum so that
would seem suspicious
and suggest that he may be involved in
the shooting next to the evidence Bullet
From the driveway
and the evidence cartridge casing seized
from a subject
is another Winchester 357 Magnum
cartridge with a fired bullet this is
one that I produced
now if you're observant you'll notice
something different about those two
cartridge cases
one of them has a case can Allure and
the other one does not we'll come back
to the importance of that in a moment
to the far right is an unfired loaded
round of Winchester 357 Magnum
ammunition
so this allows you to see not only that
case can Allure before it's somewhat
blown out by the firing process but also
it allows you to see where the cartridge
is crimped into the bullet it's crimped
into a smooth Groove below which our
three neural cantalers
here's the same slide with one exception
the evidence bullet has been rotated so
we can see the opposite side and when we
do that we see that it's covered with a
textured impact imprint so this bullet
if it has gone through a body is now
tumbling and hits something with a very
textured nature in a broadside fashion
returning to the cartridge cases the
evidence cartridge below the evidence
bullet notice that it lacks a case can
Allure whereas the cartridge is next to
it have one
now let's go in and look at the mouth of
these cartridge cases that's the opening
out of which the bullet emerged
on the left
is the evidence cartridge casing seized
from the suspect's home on the right
is one that I fired with the Winchester
lubeloid type semi-wad cutter lead
bullet
and if you look carefully you'll see
some hatching or indentations around the
evidence cartridge that are not present
in the Exemplar cartridge
it's going a little closer on the
evidence cartridge and we can see this
with a little more detail and closer
still
here's a highly magnified picture even
though this phenomena it was visible
with the naked eye and would be
invisible to would be visible to an
astute investigator with good lighting
what you're looking at is the imprint of
a cantalure
from a jacketed bullet
I remember a jacketed bullet is made of
copper which is fairly tough stuff
compared to lead and that cartridge case
that originally held this bullet was
crimped into that jacketed bullet and
left its image in the mouth of the case
so what is this saying that the
cartridge case although it's a
Winchester cartridge and although it's a
357 Magnum cartridge could not have held
the lead bullet that was found at the
scene so there is no relationship
between those two
let's look a little more about the
bullet and trace evidence
in this slide you're looking straight
down on the nose of the bullet from the
driveway
what you are seeing
are at least three things the damage
that I talked about earlier I'll
describe it as secondary damage the flat
abraded areas on the side of the nose of
this bullet but more importantly you're
looking at a fabric imprint that hatched
or ribbed pattern across the nose of
this bullet the flattened nose of this
bullet is a fabric imprint and there are
even fibers embedded in the lead of this
lubeloy bullet black synthetic fibers so
clearly the first thing this bullet hit
was fabric against a soft surface
basically a body which flattened the
nose of the bullet and then after that
it's hit something else at least twice
on its edges and yet a third time the
question is of course the sequence of
those events and what did it hit so in
summary we now know this is a bullet
that hits something soft presumably a
body it certainly was covered with
fabric what should we be doing
collecting the clothing of the decedent
if he lived at the hospital if he went
to the autopsy room from the from the
morgue to compare those fibers and that
fabric imprint with the nose of this
bullet because this is one of the
important questions is this the Fatal
bullet
let's look at the side of the bullet now
this is a highly magnified picture
through my comparison microscope bullet
comparison microscope
and I've labeled on this Photograph one
of those areas of secondary damage but
more importantly I've circled a little
area of some stringy Amber material
that's tissue
this is why I said it's important for
criminalists in other sections of the
laboratory serologists for example to
understand the needs of the Firearms
examiner and vice versa if the Firearms
examiner isn't qualified to do tissue
testing or species identification if
there were any doubt that this is human
tissue that's a step we could take of
carefully removing this little Stringer
of tissue and getting that tested in the
serology unit let's look at some more
information on this bullet
in one of these areas of secondary
damage that I've circled is some very
light yellow Almost White architectural
paint how do I know it's architectural
paint by its dull appearance there are
opacifiers in architectural paint that
are not in vehicle paint we can test it
chemically and non-destructively which
was done to demonstrate the elemental
composition and again there are
differences between architectural paint
and automotive paint so now we've got a
bullet that's gone through a body it's
got fibers it's got tissue it's then hit
a very irregular surface it's hit an
architecturally painted surface it's
light yellow the house happen to be
light yellow before it finally ended up
on the driveway so it's collected all of
these things on its journey to its final
resting place that allow it one to do a
reconstruction to approach a
reconstruction and establish this is the
Fatal bullet and now we know something
if we can locate those impact areas
about the orientation of the shooter
when we place the body in line with that
just seen an interesting example of
trace evidence on a bullet after it's
gone through a body here are a couple of
cases of bullets with trace evidence
before they strike a body and how useful
and important they can be the two
bullets you're looking at here or I'm
sorry the bullet you're looking at here
in two views is a lead semi-wide cutter
bullet we can see the rifling Engravings
on it it too happen to be five right
the reverse side of that bullet
with the finders initials in it is
heavily striated and lacks any of the
original characteristics of the gun that
fired it or even the manufacturer's
characteristics the reason is this is a
Ricochet it has struck the ground a very
abrasive surface prior to hitting the
victim
we can see some
particles or we can find particles of
soil minerals concrete asphalt depending
upon the substrate embedded in the soft
bullet metal that will allow us to
confirm what I already know by visual
appearance let's look at another one
from a large Midwestern City
this one also still being litigated so I
can't give you the city this is one of
my photographs that I prepared in
preparation for trial
of a Remington 357 Magnum
copper jacketed bullet how do we know
it's a Remington here's that scallop
that I talked to you about earlier with
the exposed lead nose and then this
large abrasive area on one side of the
bullet is the area where it made a very
shallow impact with a sidewalk how do I
know it's a sidewalk because of embedded
particles of silica sand quartz sand and
other calcium minerals that are used in
concrete here in fact is one of the test
bullets that I prepared in illustrating
how you can estimate the angle of impact
by the the nature of the damage on the
bullet and these were simply done by
setting up an experiment where I could
fire a light gun with these bullets
coming in at known angles and a recovery
device to collect them after they
rebounded a ricocheted off of the
concrete it produces a very
characteristic reproducible phenomena
what else is going to happen I showed
you bullet holes in cloth and bullet
wiping
this bullet after it rebounds off of the
sidewalk is now going to be destabilized
it's not going to be flying Point first
and tumbling
this looks at the other gives us a view
of the good side the pristine side of
the bullet the same evidence bullet that
I've just described to you so now we can
really see the Remington characteristics
showing up and the rifling engraving so
it can determine the kind of gun that
fired it if we didn't already have it
but most of all here's the jacket of the
decedent and The Bullet Hole somewhat in
quotes into that jacket we don't see the
bullet wiping that I showed you earlier
we don't see a nice round hole in fact
it looks more like a tear or a snag
those same chemical tests the diethyl
oxamide test and the sodium rhodesianate
tests could be and were used to confirm
this was a bullet hole and of course it
also matched with the entry wound into
the victim and you might say well it
should have been apparent that this was
a Ricochet the particular medical
examiner
didn't understand or appreciate that
wasn't prepared to call it a deflected
or a ricocheted bullet even though all
of these features Clearly say that
so the important thing is looking at the
trace evidence on the bullet that may be
generated by an impact prior to that
with a victim or subsequent to they can
all tell us a story about where this
bullet has been and what's happened to
it prior to or subsequent to its impact
with the body
by now you should know the proper names
of various ammunition components and
their features cartridge for example
versus a bullet
a cartridge case
Rimfire versus Center fire a primer
propellants or gun powder what head
stamps are lead bullets versus jacketed
bullets I've also given you some insight
into the great variety that exists in
ammunition how that can be useful in
evaluating shooting incidents yet there
are a number of things I haven't been
able to cover how caliber is determined
or named for example
why a 3006 a 30 30 a 300 Savage and a
308 Winchester are named as they are if
they can all shoot 30 caliber bullets of
the same basic type
there are some other sources of
information Beyond this tape I'd like to
recommend to you that are inexpensive
and very good
for example the NRA publishes a Firearms
ammunition Factbook an excellent
publication that will review and add to
much of what you've already seen
other books from the National Rifle
Association that are excellent their
firearms assembly series that will show
you the proper names and components of
each firearm you're apt to encounter
a basic book on hand loading is an
inexpensive investment that will tell
you more about propellants bullets their
design and the sort of ballistic
information that may be of value
although not published by the NRA this
also is an excellent book cartridges of
the world that will allow you to
understand something about the naming
system and what these head stamps mean
and the countries of origin
simply brochures from the manufacturers
of ammunition these are free handouts
that are available in many gun shops
I've got the Remington Winchester and
federal here that will diagram shotgun
shells and their various series of
ammunition
these don't cost you a thing
as far as gunshot wounds the top of the
line textbook in my opinion at this time
is Dr Vincent De Mayo's
excellent tax by elsevier publishing
company this should be in your library
their books on criminalistics current
books that have sections on Firearms
evidence but they're not directed
totally to Firearms evidence nonetheless
they are of considerable value the
forensic science handbook by Dr
safferstein and his other book on
criminalistics an introduction to
forensic science
Barry Fisher has Rewritten Svenson and
Wendell's book techniques of crime scene
investigation that has a unit on
Firearms evidence
and Peter DeForest Bob ganselin and
Henry Lee this excellent book also with
a section on Firearms evidence
finally an older book but also quite
good John Thornton's rewrite of Paul
Kirk's book on crime investigation
I hope you found this information useful
and informative as you play and replay
this tape and in the next series we'll
look at putting it all together in the
Reconstruction of shootings