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  • Action: The part of a firearm that loads, fires, and ejects a cartridge. Includes lever action, pump action, bolt action, and semi-automatic. The first three are found in weapons that fire a single shot. Firearms that can shootmultiple rounds ("repeaters") include all these types of actions,but only the semi-automatic does not require manual operation between rounds. A truly "automatic" action is found on a machine gun.

  • Barrel: The metal tube through which the bullet is fired.

  • Black Powder: The old form of gunpowder invented over a thousand years ago and consisting of nitrate, charcoal, and sulfur.

  • Bore: The inside of the barrel. "Smoothbore" weapons (typically shotguns) have no rifling. Most handguns and rifles have "rifling".

  • Breech: The end of the barrel attached to the action.

  • Bullets: The projectile. They are shaped or composed differently for a variety of purposes.

    • "round-nose" - The end of the bullet is blunted.

    • "hollow-point" - There is a central cavity in the bullet nose not covered by a metal jacket that creates expansion when a target is struck, creating more damage.

      • "Action 4" - Hollow-point projectile made of nonfragmenting brass with radiopaque plastic tip.

      • "Hydra-Shok" - Hollow-point projectile with soft deformable anterior and hard posterior core.

    • "jacketed" - The soft lead is surrounded by another metal, usually copper, that allows the bullet to penetrate a target more easily. A full metal jacket (FMJ) bullet has exposed lead at the base of the bullet. A total metal jacket (TMJ) bullet is fully covered.

    • "wadcutter" - The front of the bullet is flattened.

    • "semi-wadcutter" - Intermediate between round-nose and wadcutter.

    • "semi-wadcutter" - Features of both semi-wadcutter and hollowpoint.

  • Butt or buttstock: The portion of the gun which is held or shouldered.

  • Caliber: The diameter of the bore measured from land to land, usually expressed in hundredths of an inch (.22 cal) or in millimeters (9mm).

  • Cartridge: Also called a "round". Made up of a case, primer, powder, and bullet.
  • Centerfire: The cartridge contains the primer in the center of the base, where it can be struck by the firing pin of the action.
  • Chamber: The portion of the "action" that holds the cartridge ready for firing.

  • Choke: A constriction of a shotgun bore at the muzzle that determines the pattern of the fired shot.

  • Compensator: A muzzle brake, or compensator, is positioned at the end of the barrel and redirect gases outward and forward. This aids in reduces the recoil and rise of the barrel. However, gases and particulates, as well as sound, are partly directed back to the shooter so that eye and ear protection are needed..

  • Double-action: Pulling the trigger both cocks the hammer and fires the gun.

  • Double barrel: Two barrels side by side or one on top of the other, usually on a shotgun.

  • Flash suppressor: A flash suppressor, or flash hider, is attached to the muzzle of a rifle to reduce visible light from burning powder. The burning gases are more greatly dispersed as they exit the muzzle. This diminishes distracting, blinding light experienced by the shooter in darker surroundings..

  • Gauge: Refers to the diameter of the barrel on a shotgun in terms of the number of lead balls the size of the bore it would take to weigh one pound (10 gauge, 12 gauge, etc.) ".410 gauge" really refers to caliber, but is worded as such to refer to a shotgun.

  • Hammer: A metal rod or plate that typically drives a firing pin to strike the cartridge primer to detonate the powder.

  • Ignition: The way in which powder is ignited. Old muzzle-loading weapons used flintlock or percussion caps. Modern guns use "primers" that are "rimfire" or "centerfire"

  • Lands and grooves: Lands are the metal inside the barrel left after the spiral grooves are cut to produce the rifling.

  • Magazine: This is a device for storing cartridges in a repeating firearm for loading into the chamber.

  • Magnum: For rifles and handguns, an improved version of a standard cartridge which uses the same caliber and bullet, but has more powder, giving the fired bullet more energy. For shotgun loads, magnum shells have more powder and may have increased length with more shot pellets.

  • Muzzle: The end of the barrel out of which the bullet comes.

  • Pistol: Synonym for a handgun that does not have a revolving cylinder.

  • Ported barrel: A ported barrel has slots cut at the top near the muzzle to release gas behind the bullet in order to reduce muzzle lift.

  • Powder: Modern gun cartridges use "smokeless" powder that is relatively stable, of uniform quality, and leaves little residue when ignited. For centuries, "black powder" was used and was quite volatile (ignited at low temperature or shock), was composed of irregularly sized grains, and left a heavy residue after ignition, requiring frequent cleaning of bore.

  • Primer: A volatile substance that ignites when struck to detonate the powder in a cartridge. "Rimfire" cartridges have primer inside the base, while "centerfire" cartridges have primer in a hole in the middle of the base of the cartridge case.

  • Revolver: Handgun that has a cylinder with holes to contain the cartridges. The cylinder revolves to bring the cartridge into position to be fired. This is "single-action" when the hammer must be cocked before the trigger can fire the weapon. It is "double-action" when pulling the trigger both cocks and fires the gun.

  • Rifling: The spiral grooves cut inside a gun barrel that give the bullet a spinning motion. The metal between the grooves is called a "land".

  • Rimfire: The cartridge has the primer distributed around the periphery of the base.

  • Safety: A mechanism on an action to prevent firing of the gun.

  • Shotgun: A gun with a smoothbore that shoots cartridges that contain "shot" or small metal pellets (of lead or steel) as the projectiles.

  • Sights: The device(s) on top of a barrel that allow the gun to be aimed.

  • Silencer: A device that fits over the muzzle of the barrel to muffle the sound of a gunshot. Most work by baffling the escape of gases.

  • Single-action: The hammer must be manually cocked before the trigger can be pulled to fire the gun.

  • Smokeless powder: Refers to modern gunpowder, which is really not "powder" but flakes of nitrocellulose and other substances. Not really "smokeless" but much less so than black powder.

  • Stock: A wood, metal, or plastic frame that holds the barrel and action and allows the gun to be held firmly.

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History of Firearms

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