Ballistics

Firearms and Ballistics

Firearms Identificatio

Firearms Identification
A discipline mainly concerned with determining whether a bullet or cartridge was fired by a particular weapon.

Barrel B A Bullet -A) Land impression -B) Groove impression Rifling – the spiral grooves that are formed in the bore of a firearm barrel. Makes projectile spin when fired. -A) Land -B) Groove

A B B

Broach
cutter
 used
to
create
 rifling
 impressions
in
a
 barrel.


A

A

-Caliber
–the
diameter
of
 the
bore
of
a
rifled
firearm.
 The
caliber
is
usually
 expressed
in
hundredths
of
an
 inch
or
millimeters.

Example
. 22
caliber
or
9mm.


Cartridge Parts and How it Works
Cartridge Case Lead Bullet Primer Gun Powder

Bullet Comparison
Class Characteristics Different gun manufacturers use different rifling techniques. These techniques impart the class characteristics of a bullet. -Number of lands and grooves -Width of lands and grooves -Depth of lands and grooves -Pitch -Twist

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

A

Bullet Individual Characteristics
B

It is possible to determine the bullet on the left and the bullet on the right are from the same gun by matching the striations. See examples A and B

Cartridge Case Class Characteristics
Manufacture ( i.e.. Winchester) Shape ( i.e.. rimless, rimmed ) Caliber ( i.e.. 45 ACP, 9mm, 12gauge) Composition ( i.e.. brass, steel, plastic)

Cartridge Case Individual Characteristics
- Firing Pin Impressions - Breech Face Marks - Ejector Marks - Extractor Marks

Breech

Extracting Pin

Firing Pin Ejector (not shown)

Breech

When a cartridge is...