The following presents a basic lexicon of firearm terms as concisely as practical. Often the terms can become quite involved and a subject in themselves, so this is but a general guide.
Antique Firearm |
|
Any firearm (including any firearm with a matchlock, flintlock, percussion cap, or similar type of ignition system) manufactured before 1898; and any replica firearm described previously provided that (1) it is not designed or redesigned for using rimfire or conventional centerfire fixed ammunition, or (2) it uses rimfire or conventional centerfire fixed ammunition which is no longer manufactured in the United States and which is not readily available in ordinary channels of commerce. Note that certain jurisdictions, such as New York State, impose the additional condition that no ammunition be manufactured or readily available through ordinary channels of commerce, so that the classic western revolver made in 1873 would still be deemed a modern firearm since .45 Long Colt ammunition is currently produced. |
|
|
|
Assault Weapon |
|
A term of modern re-definition describing a semiautomatic weapon having characteristics of a high capacity magazine, pistol grip provision, folding stock, flash hider, bayonet lug, grenade-launching provision, or a combination of these elements. Conventionally, this refers to a select-fire military or police weapon that can discharge single shots or fire in the full-automatic mode. |
|
|
|
Black Powder |
|
The original propellant of matchlock, flintlock, and percussion firearms, which is composed of potassium nitrate, sulphur, and charcoal. It generated relatively low pressures and velocities when compared with modern ammunition, but is actually classified as an explosive. |
|
|
|
Bore |
|
The longitudinal hole within the barrel which, in the case of shotguns remains smooth, but into which in modern rifles and pistols the rifling twist is cut or impressed. |
|
|
|
Breech |
|
The portion of the firearm which contains the rearward force of discharge and ignites the cartridge or charge. |
|
|
|
Breech Loader |
|
A firearm which is loaded by placing a cartridge or projectile and powder charge at the rear of the barrel. This is secured by a breech mechanism which discharges the weapon. |
|
|
|
Centerfire Ammunition |
|
Metallic-cased ammunition containing a primer which is situated in the center of the cartridge base. |
|
|
|
Double Action |
|
A description of a multiple trigger function by which the pulling of the trigger both cocks the weapon and discharges it. |
|
|
|
Flintlock Firearm |
|
A firearm which is discharged by the action of a flint which strikes a surface to ignite a black powder charge by the action of a spark. |
|
|
|
Frame |
|
Also called the receiver, this is the main housing of the weapon containing the operating mechanism, and to which is attached the barrel, cylinder, or slide, as the case may be. The Frame or Receiver contains the serial number and is legally deemed a firearm in itself, regardless of any parts or components that may be absent. |
|
|
|
Gas Operation |
|
A firearm mechanism, generally semiautomatic or full-automatic, in which cycling of the weapon is achieved by diverting a portion of the high pressure gas generated in discharge through a port in the barrel. |
|
|
|
Machine Gun |
|
A weapon that discharges or is capable of discharging more than one round with each pull of the trigger. Machine guns fire rifle calibers. |
|
|
|
Matchlock Firearm |
|
A firearm which discharges though the action of a smoldering taper which is lowered to a pan of black powder to ignite the powder in the barrel. These represent the oldest of firearms. |
|
|
|
Muzzle |
|
The forwardmost end of the barrel. |
|
|
|
Muzzle Brake |
|
An attachment to a firearm which is designed to channel discharge gases in such a way as to diminish recoil and deflection of the weapon during firing. |
|
|
|
Muzzle Loader |
|
A firearm which is literally loaded by pouring a powder charge and driving a projectile down the muzzle of the weapon. |
|
|
|
Pistol |
|
A generic term that describes a handgun. The two basic types are revolvers and pistols. |
|
|
|
Plastic Gun |
|
Actually a popular misnomer arising after the introduction of the Glock pistol, which has a frame element molded of a polymer. In fact, the bulk of the pistol is made of steel. |
|
|
|
Percussion Firearm |
|
A firearm which is discharged through the action of a hammer which strikes a cap filled with priming compound to generate a flash that ignites the black powder in the barrel. |
|
|
|
Primer |
|
In modern ammunition this is a little brass cup filled with a volatile compound that ignites violenty under the concussive stike of a firing pin and ignites the powder contained in the cartridge case. The primer is pressed into the center of the cartridge case at its bottom. (See Centerfire Ammunition and Rimfire Ammunition.) |
|
|
|
Recoil Operation |
|
A firearm mechanism, generally semiautomatic or full-automatic, in which the cycling of the weapon is achieved by the action of mechanical recoil of component parts. Most modern semiautomatic pistols are of this design, as well as is, for example, the heavy .50 caliber military machine gun. |
|
|
|
Revolver |
|
A handgun that fires repetitively, a single shot with each pull of the trigger, through the rotation of a cylinder which holds the ammunition. Usually revolvers hold five or six shots, but some versions hold up to nine or ten, depending upon the caliber. |
|
|
|
Rifle |
|
A shoulder arm having a supporting stock and possessing a barrel into which rifling has been cut or impressed to stabilize the flight of the projectile. Rifles without the impress of actual rifling are called “smoothbore.” General types of rifle actions are bolt-action, lever-action, or semiautomatic. |
|
|
|
Rifling |
|
The spiral pattern cut into the bore of a barrel to engage and stabilize a projectile. Rifling is composed of Lands (the “raised” portion) and Grooves (the “depressed” portion). |
|
|
|
Rimfire Ammunition |
|
Metallic-cased ammunition in which the priming compound is disposed with the rim of the cartridge case. |
|
|
|
Safe Action |
|
A firearm discharge system largely introduced by Glock in which the firing pin, or stiker, is at a state of partial cock and blocked by a mechanical impediment. The action of pulling the trigger draws the stiker to full cock, releases the striker bock, and subsequently releases the spring-loaded striker to discharge the weapon. |
|
|
|
Sawed-Off Shotgun |
|
Legally termed a “short-barreled shotgun,” is a shotgun having one or more barrels less than 18 inches in length and any weapon made from a shotgun (whether by alteration, modification, or otherwise) if such weapon as modified has an overall length of less than 26 inches. This type of weapon is classed and treated as a machine gun would be and requires an ATF Class 3 License for transfer. |
|
|
|
Semiautomatic Pistol |
|
A handgun which “self-loads” itself, in that each pull of the trigger discharges a single shot of the weapon which automatically reloads its firing chamber from a magazine as a function of the recoiling action of a slide. There is actually also a semiautomatic revolver, long obsolete, which rotated the cylinder to the next shot through the action of its recoil. |
|
|
|
Short-Barreled Rifle |
|
A rifle having one or more barrels less than 16” in length and any weapon made from a rifle (whether by alteration, modification, or otherwise) if such weapon, as modified, has an overall length of less than 26 inches. This type of weapon is classed and treated as a machine gun would be and requires an ATF Class 3 License for transfer. |
|
|
|
Shotgun |
|
A shoulder arm having a smooth bore which is designed to discharge a load of multiple pellets, although they are often used with a single large projectile called a rifled slug. |
|
|
|
Single Action |
|
A description of trigger function by which the trigger fulfills the single purpose of releasing a hammer or firing mechanism which is cocked in a separate manual operation. |
|
|
|
Smokeless Powder |
|
Again, a misnomer, since it does indeed generate smoke, but gains its name for cleanness of its burning properties and the lack of the voluminous cloud that accompanies the discharge of black powder cartridges or weapons. It is classed as a propellant powder and comprises various formulations based upon nitroglycerine or nitrocellulose, generating high pressures and high velocities, and is not intended for use in black powder weapons. |
|
|
|
Submachine Gun |
|
A weapon that discharges or is capable of discharging more than one round with each pull of the trigger. Submachine guns fire pistol calibers. |
|
|
|
Suppressor |
|
An attachment to the muzzle of a firearm designed either to dampen the sound of discharge or to diminish the flash at the muzzle. The former is a Sound Suppressor, or silencer, while the latter is a Flash Suppressor. |
|
|
|
Topbreak Revolver |
|
This type of revolver, most common between the late 19th century and first half of the twentieth, opened for loading and unloading as the barrel pivoted downward at a point just in front of the cylinder to form an invereted “V.” . It literally “broke opened” by actuation of a latch at the top by the rear sight. A classic example is the Schofield revolver, or the familiar British Webley. By comparison, the modern revolver which opens to left side is said to have a “swing-out” cylinder. |