1
Q
It is a discipline of forensic science which primary concern is to determine whether or not the
submitted collected fired cartridge cases, fired bullets or other ammunition components were fired from a particular firearm.
A
Firearm identification
2
Q
It is regarded as the highest form of
an uncontestable and conclusive piece of evidence with an outmost legal significance.
A
Firearm identification or forensic ballistics
3
Q
Principle in Firearm Identification
A
- It is refined toolmarks identification.
- The natural wear and tear of the tools are involved.
- When the soft surface comes in contact with the hard surface, it leaves with the impressions
scratches from any irregularities on the hard surface. - The principle of individuality, that is no two things is absolutely identical.
4
Q
depressed portion caused by lands that can be found in the cylindrical surface of the fired bullet.
A
Land marks
5
Q
– raised or elevated portions caused by the grooves that can be found in the cylindrical surface of the fired bullet.
A
Groove marks
6
Q
found on the anterior portion of the fired bullets and caused by the forward movement of a bullet from the chamber before it initially rotates due to the rifling inside the barrel.
A
Skid marks
7
Q
found on a bullet fired though loose fit barrels wherein the
riflings are already worn out.
A
d. Stripping marks/slippage marks
8
Q
found on bullets fired from revolver due to poor alignment of the cylinder with the bore.
A
Shaving marks
9
Q
Principles Involved in Bullet Identification
A
- No two barrels are microscopically identical as to the internal surfaces of the barrels; all possess
Individual characteristics markings of their own. - When the bullet is fired from a rifled barrel, it becomes engraved by the riflings and these
engravings will vary in its minute details with every individual firearm. Therefore, the engravings
on the bullet fired from one barrel will be different from another bullet fired from another barrel.
On the other hand, the engravings on bullets fired from the same barrel will be the same. - Every barrel leaves its thumb mark or fingerprint on every bullet in it.
10
Q
found on bullets fired from revolver due to poor alignment of the cylinder with the bore.
A
Shaving marks
11
Q
are common to cartridge cases that have passed through the action of
an auto loading or repeating firearm. Striated action marks can be produced on cartridge cases
by contact with a number of different areas within the firearm.
A
striated Action Marks
12
Q
with a few exceptions,are produced when a cartridge case is fired in
a firearm. The two most common impressed action marks are firing pin impressions and
breechface marks.
A
Impressed Action Marks,
13
Q
found in the body of the shell due to the irregular makings in the chamber
A
Chamber mark
14
Q
found in the primer cup or the rim of the cartridge case caused when the primer cup struck by the firing pin.
A
Firing pin
15
Q
produced when a projecting firing pin comes into contact with a cartridge
case or shotshell during the extraction,ejection cycle.
A
Firing pin drag marks
16
Q
Secondary firing pin mark found near the firing pin mark and usually found in pistols.
A
Shearing marks
17
Q
found in extracting groove in automatic firearms produced when cartridge case comes in contact with the extractor rod of a firearm in the withdrawal of an empty cartridge case after firing
A
Extractor mark
18
Q
Located in the rim in automatic firearms produced when cartridge case comes In
contact with the ejector of a firearm after firing.
A
Ejector marks
19
Q
found on the shell caused by turning of the cartridge
A
Pivotal marks
20
Q
found at the low points of the rim of the base of the shell; caused by the
magazine lips during the loading of the cartridge into the magazine for firing
A
Magazine lip marking
21
Q
found on the base of the cartridge case as a result of the rearward movement of cartridge case during firing.
A
Breechface marks
22
Q
these are marks caused by the contact between the cartridge case and the
ejector port of the firearm.
A
Ejector port mark
23
Q
Principles Involved in Shell Identification
A
- The breechface and the firing pin of every firearm have microscopic individualities of their own.
Every firearm leaves its fingerprint or thumb mark on every cartridge it fires.
- The breechface and the firing pin of every firearm have microscopic individualities of their own.
- The whole principle of identification of shells is predicated or based on the fact that since the
breechface of every weapon must be individually distinct, the cartridge cases which fires, are
imprinted with this individuality. The Imprints of All cartridge cases fired from the same weapon
are similar, and those on cartridge cases fired from different weapons are different
24
Q
characteristics that are determinable even prior to the manufacture of firearms. They are
factory specifications and within the control of man. They serve as the basis for identifying a certain
group or class of firearms.
A
Class characteristics
25
– the diameter in which the bore was reamed. It is the distance measured
between two opposite lands inside the bore.
Bore diameter/ caliber
26
the number of lands is always equal with the number of grooves.
Number of lands and grooves
27
is dependent on the bore diameter, the bigger the caliber, the wider the width of the lands and grooves. It is the remainder of the circumference after subtracting the groove width
Width of lands
28
Width of grooves
29
it is the twisting of the lands and grooves whether clockwise or counterclockwise.
For the bullet have gyroscopic motion during its flight
Direction of twist
30
measured on the radius of the bore as seen in the cross section . It is equal to the height of the side of the lands
Depth of groove
31
the twist of lands and grooves. It also refers to the distance advanced by the riflings in complete run
Pitch of rifling
32
4RGL (four lands and grooves, the direction of twist is to the right and the width of
grooves is equal to the width of lands)
Steyr type
33
4RG2X (four lands and grooves,the direction of twist is to the right and the width
of grooves is twice to the width of lands)
Carbine type
34
– 5RGL (five lands and grooves, the direction of twist is to the right and
the width of grooves is equal to the width of lands)
Smith and Wesson type
35
6RG2X (six lands and grooves,the direction of twist is to the right and the width
of grooves is twice the width of lands)
Browning type
36
6LG2X (six lands and grooves, the direction of twist is to the left and the width of
grooves is twice the width of lands)
Colt type
37
7RG3X (seven lands and grooves,the direction of twist is to the right and the
width of grooves is thrice the width of lands)
Webley type
38
4RG3X (four lands and grooves, the direction of twist is to the right and the width
of grooves is thrice the width of lands)
Army type
39
6RG3X (six lands and grooves,the direction of twist is to the right and the
width of grooves is thrice the width of lands)
Winchester type
40
These are characteristics peculiar and not found in all other firearms. They serve as the
basis for the Identification of a particular firearm and identifiable only after the manufacture of
the firearm. These characteristics are beyond the control of the man and have random
distribution inside the gun.
Individual characteristics
41
7 Problems of Firearm Identification
1. Given a bullet; to determine the caliber and type of firearms used.
In this problem, there is a need to determine the general rifling characteristics to identify the
possible type of firearm used. The bullet must be described as Its appearance and take note of the
place of recovery (Physical Examination). Such a bullet will be submitted to PNP-Firearms and
Explosive Office (PNP-FEO) for cross matching.
2. Given a cartridge case; to determine the caliber, Name of the manufacturer and the type
of fire Arm used.
In this problem, marks found on the headstamp must be obtained to identify the manufacturer,
the year of manufacture and the possible firearm that used such type of cartridge case. The specimen
must be described and take note of the place of its recovery (Physical Examination). Such a cartridge
case will be submitted To PNP-Firearms and Explosive Office (PNP-FEO) for cross matching.
3. Given a bullet and firearm, to determine whether or not the bullet was fired from
suspected firearm Submitted.
In this problem, the physical examination will be first conducted on the submitted
specimens to determine the possible caliber of the firearm and the rifling characteristics. Then,
describe and determine whether the firearm is serviceable and capable of discharge. If the
markings are comparable and there is a possibility that the bullet came from the firearm, there
is a need to obtain standards from the submitted firearm. After obtaining the test fired bullet as
a microscopic examination will now be conducted.
4. Given a fired cartridge case and a suspected firearm, to determine whether or not the
cartridge case was fired from the suspected firearm submitted.
In this problem, a physical examination will be first conducted on the submitted specimens
to determine the possible caliber of the firearm and the markings present on the cartridge case.
Then, describe and determine whether the firearm is serviceable and capable of discharge. If
the markings are comparable and there is a possibility that the cartridge case came from the
firearm, there is a need to obtain standards from the submitted firearm. After obtaining the test
fired cartridge case as standard, a microscopic examination will now be conducted.
5. Given two or more bullets, to determine whether or not the bullets were fired from only
one weapon.
In this problem, a physical examination will be conducted to all submitted specimens
(consider Problem # 1). Group submitted bullets based on their caliber and rifling characteristics.
Thereafter microscopic examination will be conducted to bullets of the same caliber.
6. Given two or more fired cartridge cases, to determine whether or not the cartridge cases
were fired from only one weapon.
In this problem, a physical examination will be conducted to all submitted specimens
(consider Problem # 2). Group submitted a cartridge case based on their caliber and the
similarities of impressions. Thereafter microscopic examination will be conducted to cartridge
cases of the same caliber
7. Given a firearm, to determine whether : it is serviceable or not.
In this problem, the submitted firearm will be examined to determine its operability and functionality.
It also includes an examination of tampered serial numbers and the changing of major parts of a firearm
42
For every one (1) evidence bullet, there is a need to obtain three (3) to five (5) standards
True
43
Results of Cartridge Case Identification
a. Exhibit 1 (cartridge case) was identified as having been fired by Exhibit 2 (firearm). This
conclusion reached if the action marks present on the questioned cartridge case are determined
to be because of the actual firing process.
b. Exhibit 1 (cartridge case) could neither be identified nor eliminated as having been fired by
Exhibit 2 (firearm). This conclusion reached if the cartridge case lacks sufficient action marks to
be identified as having been fired by the questioned firearm or the firearm in question fails to
produce reproducible Individual characteristics on standards. All general class characteristics
such as caliber and firing pin shape would have to agree
c. Exhibit 1 (cartridge case) was not fired by Exhibit 2 (firearm). This conclusion can sometimes be
reached when the submitted cartridge case exhibits very good individual characteristics that are
very dissimilar to those produced on standards. However, consideration must be given to the
possibility that the firearm in question could have changed significantly be reached. can be
accounted for, a negative conclusion will be reached
d. Exhibit 1 (cartridge case) was identified as having passed through the action of Exhibit 2
(firearm). This conclusion can be reached if the cartridge case is found to have action marks that
result from simply loading and /or unloading a cartridge case in a firearm.
44
Purpose of Three Standards
1. First is for preliminary
2. Second is for confirmation
3. The third is for the conclusion
45
it is principally composed of burned and unburned particles from
the explosive primer, the propellant, as well as components from the bullet, the cartridge case
and the firearm used. The
common method used is by means of swabbing the bore of the firearm.
Gunpowder Residue Analysis –
46
most important parts of the firearm, is cylindrical in shape with projecting
length. It is made of a carefully selected solid piece of metal, fitted for its chemical and metallurgical
structure which has the capability to withstand explosion and tremendous pressure coming from the
expansion of heated gas coming from burning gunpowder.
Barrel
47
solid piece of cylindrical metal is drilled by a special deep-hole drill; through
the center of which lubricating oil is forced under pressure.
Drilling stage
48
Removes Scars and Scratches left by the drilling operation. The reamer used
is slightly greater in diameter than that of the drill therefore removes excess metal from the entire
surface of the bore. There are three types of reamers used in reaming the bore of the barrel;
roughing, finishing and burnishing.
Reaming stage
49
the creation of the land and grooves inside the bore to improve the projection of
the bullet during firing.
Rifling stage
50
the oldest method of making riflings invented in Nuremberg at around
1942. A hook cutter is pulled through the bore numerous times and indexed after every stroke to
produce the riflings.
Cut rifling technique
51
broaching cutter that cuts longitudinal spiral grooves inside the barrel. It
produces the desired number of lands and grooves in a single stroke.
Broaching system
52
produces the desired number of lands and grooves simultaneously but in a
different manner. It does not cut longitudinal spiral grooves inside but it produces the same by
depressing a portion of the internal surface of the bore thus creating the grooves.
Button system
53
it starts with a reusable mandrel that carries the reverse image the
entire length of the bore and uses it to produce the desired rifling profile. The lands and grooves
are visible in reverse, spiraling the full length.
Hammer-forged System
54
this is the polishing operation wherein a lead plug is used in removing many of
the larger imperfections due to the cutting of forming operation.
Lapping stage
55
it starts with a reusable mandrel that carries the reverse image the
entire length of the bore and uses it to produce the desired rifling profile. The lands and grooves
are visible in reverse, spiraling the full length.
Hammer-forged System
56
consists of the number of the helical grooves cut on the surface of the bore, it includes the
lands and the grooves. The lands and grooves are running parallel with one another concentrically.
1. To impart motion of rotation to a bullet
2. To ensure stability in flight.
3. So that the bullet will travel nose towards the target.
Riflings
57
refers to the raised metal between grooves,
Lands
58
the depressed portion of the gun barrel width of lands and grooves
Grooves
59
it is equivalent to the height of lands.
Depth of grooves
60
the number of inches traveled by the bullet to make one complete run. It is also
called the rate of twist. It denotes the distance that it takes for the rifling to complete 1 revolution
and therefore how long it takes a fired bullet to rotate 360 degrees.
Pitch of rifling
61
the direction of twist whether left or right.
Twist of rifling
62
this rifling feature defined sharp lands and grooves. The bullet is slightly
larger than the bore and is therefore forced into this shape producing marks on the bullet known
as rifling marks
Conventional rifling
63
It has a much less defined set of lands and grooves and is generally
smoother in shape. This results in less resistance for the bullet when travelling down the barrel,
higher bullet velocities and cleaner operation. The smoother bore deforms the bullet less than
conventional rifling and supposedly leaves it more aerodynamically stable.
Polygonal rifling
64
portion of the firearm against which the cartridge case and the primer are
forced backwards upon firing while the firing pin is the part of the firearm which strikes the primer of the
cartridge.
Breechface
65
Factors that affect Breechface Impression
1. Powder charge of the cartridge
2. The softness of the primer cup and the surrounding brass
3. The sharpness of the striations on the breechblock
4. Presence of oil, grease or foreign matters on the Block
5. Factory stampings on the cartridge head
3rd Year 2nd semester
flashcards
Decks in class (18)
# Cards
-
Lie Detection Techniques Prelim116
-
Ballistic50
-
Vice And Drugs38
-
FIRE DETECTION31
-
TECHNICAL ENGLISH 233
-
Lie Detection Quiz27
-
CLFM54
-
LAW 232
-
Drugs Quiz27
-
Ballistic Midterm101
-
Ballistic Prefinal65
-
Fire Midterm89
-
CDI821
-
Dispute0
-
Vice And Drugs59
-
Law Midterm3
-
Fire Arson prefinal16
-
CLFM 🤨58
