BALLISTICS

1. BALLISTICS Firearms and Cartridges

2. Terms • Ballistics: the study of bullets and firearms • Firearms: a weapon capable of firing a projectile using a confined explosive

3. History • Gunpowder 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

4. Early Weapons • Matchlock: • 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

5. Early Weapons (cont.) • Flintlock: • These weapons used sparks from a chip of flint to ignite the gunpowder • These weapons were muzzle-loaders

6. Percussion Firing • Replaced the flintlock method of firing • Started 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

7. Semiautomatic vs. Fully automatic • A semiautomatic fires only one bullet per pull of the trigger • A fully automatic fires repeatedly as long as the trigger is pressed • In both weapons, the empty cartridge ejects and the next cartridge advances automatically

8. Hand Guns • Designed 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

9. Single vs Double Action Revolvers • Single 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

10. Semiautomatic Pistol • Hold up to 10 cartridges in a magazine (a.k.a. clip), which is locked into the grip of the firearm

11. Long Guns • Require the use of two hands for accurate firing; include: • Rifles—fire bullets • Shotguns—fire either small round pellets (shot) or a single projectile (slug)

12. Rifles • Bolt Action: manually loaded and unloaded by rotating a bolt into position • Lever Action: manually loaded and unloaded by an external lever

13. Shotgun • Pump Action: features a movable forearm which is manually actuated in motion parallel to the barrel by the shooter

14. Rifling • To 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

15. 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

16. Cartridge • A 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

17. Caliber • Bullets and their cartridges are named by caliber and length • The 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

18. Caliber (cont.) • Sometimes calibers can be measured in mm • Caliber also refers to the diameter of the inside of a firearm’s barrel • The caliber of ammunition should match the firearm that shoots it

19. How a Firearm Works The tiny explosion causes the anvil to deliver a spark to the main gunpowder supply The firing pin hits the base of the cartridge and ignites the primer powder Pull the trigger

20. 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