Firearms Terms
ACP: An abbreviation for Automatic Colt Pistol. Used in conjunction with caliber designations, e.g., .45 ACP cartridge.
ACTION: The physical parts of a firearm that allow it to be loaded, fired, and unloaded.
AUTOMATIC: A term that is used to describe a firearm that uses the energy produced from the firing of ammunition to do the following:
1. Move the slide to the rear of the frame. 2. Eject the spent case out of the ejection port. 3. Grab a new cartridge from the magazine and load it into the chamber as the slide moves forward. 4. Cock the hammer or internal firing mechanism and fire the gun as the trigger is pulled.
BACKSTRAP: The rear, verticle portion of the pistol frame that lies between the grip panels.
BALLISTICS: The scientific study of the flight of projectiles. Specifically, there are three kinds of ballistics: (a) External---how a bullet behaves in flight after it leaves the barrel of a gun ; (b) Internal---the mechanical and chemical processes that occur after the trigger is pulled, but before the projectile leaves the barrel; (c) Terminal---what happens when the projectile strikes the target.
BARREL: The metal tube that contains the projectile after it is fired and allows it to travel out of the gun to the target.
BORE: The inside of the barrel which has lands and grooves which are together commonly called rifling.
BREECH: The rear-most end of the barrel opposite the muzzle.
BULLET: The projectile that is fired from the gun, usually copper clad.
CALIBER: The approximate diameter of a projectile, usually expressed in hundreths of an inch. Caliber also refers to the distance between the lands and grooves in the bore of a firearm, e.g. .22 cal.
CARTRIDGE: A complete unit of ammunition which includes the case, primer, powder charge, and projectile.
CENTER-FIRE: A cartridge that has the primer located in the center of the base of the case.
CHAMBER: The part of the firearm into which the cartridge is inserted prior to firing.
COCK: To ready the firing mechanism of a gun.
CYLINDER: The part of a revolver that holds the ammunition in individual chambers that are rotated into firing position by the action of the trigger or hammer.
DOUBLE-ACTION: A type of pistol action in which pressing the trigger will both cock and release the hammer or internal firing mechanism.
DOUBLE ACTION (DA): The trigger pull is longer and heavier than Single Action (SA), but the user can cock the hammer first if they want to fire in "Single Action Mode." If the gun is semi-automatic, the first shot is DA, subsequent shots are SA due to the slide cocking the hammer for you, resulting in a different trigger feel and a shorter trigger reset. Examples are: Beretta 8045, Beretta 96, Heckler and Koch USP series, etc.
DOUBLE ACTION ONLY: Any Double Action gun which does not allow pre-cocking the hammer because the hammer won't stay cocked, and is often bobbed or hidden. No decock is ever needed, and trigger pull is consistent between first and subsequent shots.
DRY FIRE: The manipulation of the trigger and/or slide of an unloaded gun. Used to practice trigger control, presentation, and reloads.
EJECTOR or EXTRACTOR: The part of a pistol, rifle, or shotgun which extracts or ejects the empty case or a cartridge from the gun.
FIRING PIN: The part of a gun that strikes the primer, firing the gun. Motion may be imparted to the firing pin by striking it with a hammer, or it may itself be spring-loaded and released.
Grooves: Grooves are shallow, recessed, spiral cuts that together with the lands make up the rifling in the bore of a barrel.
HAMMER: The part of a pistol that pivots on an axis at the rear of the frame, that when activated by the trigger, is released to strike the firing pin. The hammer can be visible, bobbed, or internal.
HANG FIRE: A perceptible delay in the ignition of a cartridge after the primer has been struck by the firing pin or hammer. This is also commonly known as a "Slow Cook".
LAND: The raised portion of rifling opposite the grooves inside the barrel.
MAGAZINE: A device for holding multiple cartridges to be loaded into a repeating gun's chamber. A magazine can be a fixed, non-removable part of the gun, or it can be a detachable box. A magazine is sometimes improperly referred to as a clip.
MISS FIRE: A failure of the cartridge to fire after the primer has been struck by the firing pin or hammer.
MUZZLE: The front end of the barrel from which the fired projectile exits. The opposite of the breech.
PARTRIDGE SIGHT: A type of sight designed by E.E. Partridge in the late 1800's that is generally used on handguns. It has a rear sight with a square notch and a front sight consisting of a thick blade that is flat on top.
PISTOL: A short barreled gun that is designed to be held, aimed, and fired with one hand.
PLINKING: Informal shooting a variety of targets.
REVOLVER: A pistol that has a rotating cylinder containing a number of firing chambers. The action of pressing the trigger or cocking the hammer will rotate the cylinder and line up a single firing chamber with the barrel and firing pin.
