Ballistics

Ballistics

Definition:

  • Firearm: A weapon capable of firing a projectile using a confined explosive.

What Ballistics Can Tell Us?

  • Type of firearm used

  • Caliber of bullet

  • Angle of impact from shooter to bullet

  • Number of bullets fired

  • Where shooter was firing

  • If firearm was used in a previous crime through serial numbers

Firearm Types

Handguns:

  • Can be fired single handedly

  • Further classified as semi-automatic or fully automatic

  • Have a rotating cylinder to store bullets

  • Semi-automatic pistols and revolvers: bullets loaded into magazines/clips

Other Types:

  • Pistols

  • Revolvers

  • Rifles

  • Shotguns

Long Guns

  • Requires 2 hands

  • Rifles fire bullets

  • Shotguns fire pellets or a slug

  • Shotgun pellets are separated from gun powder by wad

Cartridge Diagram

  • Bullet

  • Casing

  • Gun Powder

  • Primer

Identifying Firearms

  • Every weapon leaves its own unique markings on a bullet and cartridge it was fired from.

  • Striations: Scratch marks left

  • Breach marks: Marks left on fired cartridges

Gunshot Residue (GSR)

  • A collection of tiny particles that are released when a firearm is discharged.

  • It may reside on things.

How a Firearm Works

  1. Trigger is pulled

  2. Firearm hits base or cartridge

  3. Pressure of ignition pushes bullet from the casing and into the barrel on firearm

  4. Bullet follows the patterns of barrel and spirals out

Definitions

  • Caliber: Diameter of bullet

  • Semi-automatic: 1 bullet per trigger

  • Automatic: Lots of bullets fire per trigger

  • Pellets: Small, round projectiles used in shotguns

  • Slug: A very heavy projectile used in shotguns

  • Wad: Separates pellets from gun powder

  • Projectile: Any object thrown from a weapon, e.g., a bullet; most common projectile used in handguns and rifles

  • Cartridge: Ammunition that consists of the projectile, casing, primer, gunpowder, etc.