1. Firearms
Identification
Mr. Tomasevich Forensics

2. Firearms Identification
A discipline mainly concerned with determining whether a ______ or ________ was fired by a particular _______.

3. Barrel
-A) B
-B) Bullet A
-A) _____ impression
-B) ______ impression
Rifling - the _______
grooves that are formed in A
the bore of a firearm
barrel. Makes projectile ______ when fired. B B

4. ______ cutter used to create _______
impressions
in
a
 barrel.

A
 
-_______
-the
diameter
of

the
bore
of
a
rifled
firearm.
 The
caliber
is
usually
 A
expressed
in
hundredths
of
an
 inch
or
millimeters.

Example
. 22
_______
or
9___.


5. Cartridge Parts and How it Works

6. Bullet Comparison Class Characteristics
Different gun manufacturers use different
rifling techniques. These techniques impart the class characteristics of a bullet. -
-_______ of lands and grooves
________ of lands and grooves - -

7. Bullet Individual Characteristics
•A cross section of a gun barrel will show small
grooves or striations all along the lands and grooves
( )
•These are created when the barrel is rifled. No _____ gun barrels have the exact same markings.
•These markings leave _______
striations or impressions on a
bullet. This allows a bullet to be
traced back to a _________ firearm.

8. Bullet Individual Characteristics
It is possible to determine the bullet on the ____ and the bullet on the ______ are from the same gun by matching the _____________. See examples A and B

9. Cartridge Case Class Characteristics
______________ ( i.e.. Winchester)
________ ( i.e.. rimless, rimmed )
______ ( i.e.. 45 ACP, 9mm, 12gauge)
__________ ( i.e.. brass, steel, plastic)

10. Cartridge Case Individual Characteristics- - - -

11. Ejector (not shown)

12. When a cartridge is fired, the explosion forces the bullet down the barrel and the shell casing is forced back against the _______. This leaves impressions unique to the individual gun’s _______ on the shell casing.

13. Examples of Breech Markings

14. Firing Pin Marks In order to fire the cartridge, ________
must first be ignited. To accomplish this a ______ ____ strikes the center ring of the cartridge. This will in turn leave a _______ impression that is unique to the ________ of that particular gun.

16. Extracting Pin and Ejector Marks
The extracting pin
and ejector throw the spent shell casing from the chamber of the gun.
These leave marks on the shell casing that are unique to those parts on that particular firearm.

17. Shotgun identification
Shotguns have ________ barrels with not rifling. Therefore there are no land or groove marks left on the bullet. Identification can still be made by comparison of ________________ markings on shotgun shell.

18. REVIEW
Define the term “Firearm Identification”.

19. REVIEW What is the purpose the lands and
grooves that comprise the rifling in a gun barrel?

20. REVIEW
How do you determine the caliber of a gun?
Caliber

21. REVIEW
What are the four parts of a cartridge?

22. REVIEW Pretend you recover a bullet from a
crime scene. How could you determine what kind of gun fired that bullet? • • •

23. REVIEW
What type of individual characteristics can be used to match a shell casing back to an individual gun that fired it? • • • •

24. REVIEW
What is the difference between class characteristics and individual characteristics?