Ballistics Projectiles Projectile Definition any material that travels

Ballistics

Projectiles

Projectile Definition: any material that travels with the ability to injure Energy is dependent on the velocity, mass, and distance traveled by projectile Not all projectiles come from fire arms!!!

Kinetic Energy Formula: KE = mv 2 2 Velocity usually plays the major role in the kinetic energy Over whelming weight (mass ) can makeup for a slow velocity (Hit by a car) Shape of a projectile will determine how well an object can slice through atmosphere and hence how well it will maintain velocity

Fire Arms

Fire Arms Identification Definition: A discipline mainly concerned with determining whether a bullet or cartridge was fired by a particular weapon

Collection of Fire Arm Evidence 1 st: Always assume that the fire arm is loaded ◦ Do NOT assume gun is safe until it is processed evidence 2 nd: Pick up carefully at grip and make sure to keep fire arm pointed to the ground or up away from anyone. ◦ Grip of a gun is hard to find or collect evidence from therefore you maintain integrity of physical evidence 3 rd: Never poke or put anything in the barrel it may destroy evidence. To make the gun safe remove ammunition. 4 th: Take note of amount of ammunition remaining in chamber and cartridge along with number of ammunition missing. 5 th: Have the gun confirmed by a second professional that all ammunition has been removed

Landmarks B A A B B Barrel Contains: A) Land B) Grooves Bullet Contains: A) Land Impressions B) Groove Impressions Rifling: the spiral grooves that are formed in the bore of a fire arm barrel, which makes the projectile spin when fired Caliber: diameter of the bore of a rifled fire arm which is measured from one land to another land (measured in mm or hundredths of an inch)

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

Bullet Comparison Class Characteristics ◦ Number of lands and grooves ◦ Width of lands and grooves ◦ Depth of lands and grooves ◦ Twist ◦ Cartridge Case (manufacturer, shape, caliber, composition) Individual Characteristics ◦ ◦ ◦ Machine markings Striations Impressions Firing Pin Impressions Extractor and Ejector Marks

Class Characteristics Different gun manufacturers use different rifling techniques which are shown in the class characteristics of the bullet Number of lands and grooves Width of lands and grooves

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

Bullet Individual Characteristics Machine markings: a cross section of a gun barrel that shows groove or striations along the lands and grooves of the bullets These are created when a barrel is rifled. No two guns have the exact same rifling

Matching Striations B A

Cartridge Case Individual Characteristics Firing Pin Marks: To fire the cartridge the primer must be ignited. This is accomplished by the firing pin hitting the center ring of the cartridge which is unique

Cartridge Case Individual Characteristics (Cont’d) Extractor and Ejector Marks: The extracting pin and ejector throw the spent casing from the chamber of the gun which leave individual characteristics on the shell casing that can be used for identification of the gun which fired that casing

Gun Parts where Individual Characteristics are created Breech Firing Pin Extracting Pin

Shot Gun Exception Shotguns have smooth barrels with not rifling. Therefore there are no land or groove marks left on the bullet. Identification can still be made by comparison of extractor/ ejector markings on shotgun shell.