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 shoot
multiple 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.
"jacketed" - The soft lead is surrounded by another metal,
usually copper, that allows the bullet to penetrate a target more easily.
"wadcutter" - The front of the bullet is flattened.
"semi-wadcutter" - Intermediate between round-nose and
"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,
- 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
Choke: A constriction of a shotgun bore at the muzzle that determines the
pattern of the fired shot.
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
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"
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.
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.