Ballistics 9

Lecture 9

Cartridge case

-       A container usually metal and usually cylindrical in shape to be loaded with primer, powder charge (propellant) and bullet.

-       Components of cartridge:

o   Primer- Volatile compound that ignites when struck by guns firing pin.

o   Propellant = Gun powder (forms gases which push the bullet out of the cartridge and the gun barrel.

o   Case

o   Projectile

Instrumental analysis

Breech Face Mark

Firing Pin Mark

Ejector Mark

Extractor Mark

Magazine Lip Mark

Chamber Mark

Slide Drag Mark

Instrument used

-       Disputed cartridge case can be linked with the disputed firearm with the help of examination various toolmarks on cartridge case with the help of instruments:

-       IBIS

-       Comparison Microscope

-       Stereo Microscope

-       Calliper

Principles of Cartridge Case Examination

The breech face and firing pin of every single firearm have individual microscopic individualities of their own;

Every firearm leaves its fingerprint or thumbprint on every cartridge it fires;

That, since the breech face of every weapon, has the individual distinction, the imprints of all cartridge cases fired from the same weapon are the same

Collection of cartridge case

-       Empty cartridges: Use tweezers to lift the cartridge case wrap in cotton and place in separate air tight containers to prevent cross-contamination.