Bullet Trajectory

Notes on page 68-69

Welcome to

Ballistics!

Sharpshooter

You’ll enjoy this

one!

Parts of the Gun• Click to add text

Magazine

Trigger

HammerFiring Pin

Rifled barrel

Anatomy of a Bullet

Flash Hole

How is a Bullet Fired?• Pull the trigger• Hammer is pulled back• Hammer is pushed forward• Hits the firing pin• Hits the primer• Causes primer powder to spark• Spark goes through flash hole and ignites

rest of gunpowder

How a Revolver Works

What happens to evidence?• Bullets

– Shot forward with a given force– Stop when sufficient force is acted upon

it (hits something that slows it down, gravity pulls it down)

Land

Groove – the little lines etched in the grooves are the striations

What happens to evidence?• Cartridge cases

– Ejected from semiautomatic guns (usually to the right)

– Remain in cylinder in revolvers

Semiauto vs Revolver

Individual or Class?• There are class characteristics, but

when you look at striations, bullets are individual evidence

• Cartridge casings are individual because of the extractor and ejector marks

Bullets - Individual!• Play video!

Cartridge Cases - Individual

Important Forces• Forward force of the bullet• Downward force of gravity• To some extent:

– Wind speed

Bullet Trajectory• Trajectory: path of the propelled

bullet

Determining Location of Shooter

• Need 2 reference points to make a straight line– Bullet holes in an object such as a wall,

window or furniture– Bullet holes in a victim (entrance and

exit count as two!)• Straight line tells investigators that

shooter was somewhere on that line

Trajectory