BALLISTICSFirearms and Cartridges

TermsBallistics: the study of bullets

and firearmsFirearms: a weapon capable of

firing a projectile using a confined explosive

HistoryGunpowder was invented by the

Chinese more than 1,000 years ago

It is a combination of potassium nitrate, charcoal, and sulfur that expands to 6x its size when ignited

The first guns were developed in Europe during the 14th century

Early WeaponsMatchlock:

◦These weapons had wicks to carry a flame to the gunpowder

◦These weapons were muzzle-loaders

◦The powder and projectile were put down the firearm’s barrel (muzzle) and packed into place

Early Weapons (cont.)Flintlock:

◦These weapons used sparks from a chip of flint to ignite the gunpowder

◦These weapons were muzzle-loaders

Percussion FiringReplaced the flintlock method of

firingStarted with the introduction of a

cartridge, which is a case that holds a bullet, a small amount of primer powder, and the gunpowder

A hammer hits the primer powder, which explodes to ignite the gunpowder

Cartridges are loaded opposite the barrel (breech) so these weapons are called breech-loaders

Semiautomatic vs. Fully automaticA semiautomatic fires only one

bullet per pull of the triggerA fully automatic fires repeatedly

as long as the trigger is pressedIn both weapons, the empty

cartridge ejects and the next cartridge advances automatically

Hand GunsDesigned to be fired with one

hand and are called pistols; classified into:◦Revolvers--Hold 6 cartridges in a

cylinder that turns as the weapon is fired

◦Semiautomatic Pistols

Single vs Double Action RevolversSingle Action revolvers require

cocking the hammer and pulling the trigger to release the hammer

In Double Action revolvers the trigger cocks the hammer and causes it release

Semiautomatic PistolHold up to 10 cartridges in a

magazine (a.k.a. clip), which is locked into the grip of the firearm

Long GunsRequire the use of two hands for

accurate firing; include:◦Rifles—fire bullets◦Shotguns—fire either small round

pellets (shot) or a single projectile (slug)

RiflesBolt Action: manually loaded

and unloaded by rotating a bolt into position

Lever Action: manually loaded and unloaded by an external lever

ShotgunPump Action: features a

movable forearm which is manually actuated in motion parallel to the barrel by the shooter

RiflingTo increase the accuracy of a

shot, a projectile should have a twist

The barrel of a weapon has raised areas (lands) and indentations (grooves) that cause the bullet to spiral as it exits

Rifling (cont.)Rifling refers to the pattern left

on a bullet by the lands and grooves

Because it is impossible to produce two identically rifled gun barrels, a bullet can be matched to the specific gun from which it was fired

CartridgeA typical cartridge

contains:◦Bullet◦Primer powder◦Gunpowder◦Casing material◦Anvil and flash hole: which delivers

the explosive charge from the primer to the gunpowder

◦Headstamp: identifies the caliber and manufacturer

CaliberBullets and their cartridges are

named by caliber and lengthThe caliber is a measure of the

diameter of the cartridge measured in hundredths of an inch

Common calibers include .22, .25, .357, .44 and .45

Caliber (cont.)Sometimes calibers can be

measured in mmCaliber also refers to the

diameter of the inside of a firearm’s barrel

The caliber of ammunition should match the firearm that shoots it

How a Firearm Works

Pull the trigger

The firing pin hits the base of the cartridge and ignites the primer powder

The tiny explosion causes the anvil to deliver a spark to the main gunpowder supply

How a Firearm Works (cont.)

The gunpowder ignites and the explosion pushes the bullet from the casing and into the barrel where it follows the lands and grooves pattern and begins its spiral before it exits