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Glossary

Glossary firearm

A technical reference glossary for the firearms world

all4shooters.com - Technical supervision: Franco Palamaro

Letters: A - E



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A

  
ACTION

The combination of the parts of a firearm that enable it to be loaded, discharged and unloaded.

     
ACTION, AUTOMATIC

A firearm that loads, fires and ejects cartridges continually as long as the trigger is depressed and there are cartridges available in the feeding system (i.e., magazine, ammunition belt or other such mechanism). Automatic action firearms are machine guns, and as such, are severely restricted or unlawful to possess by civilians in most countries and states, their use reserved to law enforcement and the military.

  

ACTION, BOLT

A firearm, typically a rifle, that is manually loaded, cocked and unloaded by pulling a bolt mechanism up and back to eject a spent cartridge and load another. Bolt-action firearms are popular for hunting, target shooting and biathlon events. A bolt-action rifle allows the shooter maximum accuracy, but may be too slow for some shooting sports.

ACTION, BREAK

A firearm that loads and unloads by means of opening the action by pivoting the barrel(s) down and away from the breech while activating a release lever. Most commonly used in single-shot and double-barreled shotguns and rifles.
  

ACTION, LEVER

A firearm, typically a rifle, that is loaded, cocked and unloaded by an external pivoting lever usually located below the receiver.

Note: The type of rifle used in most Western movies is a lever-action.
  

ACTION, PUMP

A firearm that features a movable forearm that is manually actuated to chamber a round, eject the casing and chamber a subsequent round. Also known as Action, Slide.
     

ACTION, SEMI-AUTOMATIC 

A firearm in which each pull of the trigger results in a complete firing cycle, from discharge through reloading of the chamber. It is necessary that the trigger be released and pulled for each cycle. These firearms are also called “auto-loaders” or “self-loaders.” The discharge and chambering of a round is either blowback operated, recoil operated or gas operated.

Note: An automatic-action firearm loads, discharges and reloads as long as ammunition is available and the trigger is depressed. A semi-automatic firearm only discharges one cartridge with each squeeze of the trigger.

  

AMMUNITION

A loaded cartridge, consisting of a primed case, propellant and a projectile. Among the many types of ammunition are centerfire, rimfire and shotshells. Caseless ammunition also exists, although still in experimental stage.
See also CARTRIDGE
.

  

AMMUNITION-CENTERFIRE

Ammunition that contains the primer in the center of the base of the case. Among the most common centerfire handgun cartridges are the .38 Special, .357 Magnum, .40 S&W, .45 ACP, and the 44 Magnum. Common rifle cartridges include the .223 Remington, .308 Winchester, .30-06 Springfield, 7.92×57mm Mauser, and the 6,5 × 55mm SE.

  

AMMUNITION-RIMFIRE

Ammunition that contains the primer compound in the rim of the case and is fired by striking the rim and igniting the primer. The most common rimfire cartridge is the .22 Long Rifle.

  

AMMUNITION, SMALL ARMS

A military term used to described ammunition for firearms with bores (the interior of the barrel) not larger than one inch in diameter.
  

ARMS, SMALL

Any firearm capable of being carried by a person and fired without additional mechanical support.
  

ARMOR PIERCING

The capability of a projectile of any sort to pierce through individual or vehicle ballistic protections. See also BULLET.




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B

  
BACKSTRAP-CURVED
The rear grip area of a pistol that features a curved profile designed to fill the palm of the hand and aid in control and comfort while handling the gun.
  
BACKSTRAP-STRAIGHT
The rear grip area of a pistol that features a straight profile.
  
BALLISTICS

The science of studying projectiles. Ballistics can be “interior” (inside the gun), “exterior” (in the air), or “terminal” (at the point of impact). Ballistic comparison is the attempt to microscopically match a bullet or fired cartridge case to a particular firearm, usually for forensic reasons.

See also BULLET IMPRINTING.
  

BARREL

That part of a firearm through which a projectile travels. The barrel may have a rifled bore (i.e., with spiral grooves on the interior) or smooth bore (i.e., a smooth interior barrel with no grooves, usually a shotgun).

See also BORE, RIFLING.
  

BARREL BUSHING

A cylindrical piece positioned in the front of the slide in many semiauto pistols that precisely aligns the barrel for each shot.

  

BB

Spherical shot having a diameter of .180” used in shotshell loads. The term is also used to designate air rifle shots in the .175” diameter range or the 6mm plastic pellets propelled by Airsoft replicas.
  

BENCHREST

A table specifically designated by eliminate as much human error as possible by supporting a rifle for competitive shooting or sighting-in purposes. The term has also come to designate a shooting sport mandating the use of such a support.
  

BIG BORE

In America, any firearm using a centerfire cartridge with a bullet .30” (7.62mm) in diameter or larger.
  

BIRDSHOT

Small pellets, usually lead or steel, used in shotshells ranging in size from #12 (less than the diameter of a pencil point) to #4 (about .10”, or 2,5mm, in diameter) used for bird and small-game hunting.

See also SHOTSHELL.
  

BORE

The interior of the barrel forward of the chamber. It can be rifled or smooth.
  

BORE DIAMETER

On rifled barrels, the interior diameter of the barrel from the tops of the lands (the highest point). On a smooth-bore barrel, the interior dimension of the barrel forward of the chamber (not including the choke on shotgun barrels).
  

BUCKSHOT

Large lead pellets ranging in size from .20” to .36” - from 5 to 9,1 mm- diameter, normally loaded in shotshells used for deer hunting.

See also SHOTSHELL.
  

BULLET

A non-spherical projectile to be used in rifled barrels. 

     

BULLET, ARMOR PIERCING

A projectile or projectile core that is intended to pierce steel armor. Such ammunition is severely restricted or unlawful to possess by civilians in most countries and states, its use reserved to law enforcement and the military.

     

BULLET, DUMDUM

A British military bullet developed in India’s Dum-Dum Arsenal in 1897-98. It was a jacketed .303 caliber rifle bullet with the jacket nose left open to expose the lead core in hopes of greater effectiveness. Further development of the bullet was not pursued because the Hague Convention of 1899 outlawed such bullets for warfare. Beyond the myth, it is essentially the structure of a standard hunting bullet.
  

BULLET IMPRINTING

The grooves embossed into a bullet by barrel rifling. 

Note: When a bullet travels down the barrel, the spiral grooves (or rifling) leave an imprint on the bullet. The matching of the marks on a bullet to the rifling of a particular firearm can be an important tool for law enforcement in determining whether a bullet was fired from a particular firearm.

See also BALLISTICS.
     

BULLET, FULL METAL JACKET

A projectile in which the bullet jacket (a metallic cover over the core of the bullet) encloses most of the core, with the exception of the base. They are used mostly for target shooting and by the military.
     

BULLET, HOLLOW POINT

A bullet with a cavity in the nose, exposing the lead core, to facilitate expansion upon impact. Hollow point cartridges are used for hunting, self-defense, police use and other situations to avoid over-penetration.
     

BULLET, WADCUTTER

A generally cylindrical bullet design having a sharp-shoul-dered nose intended to cut paper targets cleanly to facilitate easy and accurate scoring.
  

BUTT

On handguns, it is the bottom part of the grip. On long guns, it is the rear or shoulder end of the stock.

  

BUTTPLATE

The bottom surface of a magazine. It retains the spring and the follower within the magazine and is usually removable for cleaning and maintenance.




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C

  
CALIBER

A term used to designate the specific cartridges for which a firearm is chambered. It is the approximate diameter of the circle formed by the tops of the lands of a rifled barrel. It is the numerical term included in the cartridge name to indicate a rough approximation of the bullet diameter. It is expressed in either fractions of an inch (.30 cal.) or millimeters (7mm).
  

CARBINE

A rifle of short length and light weight originally designed for horse-mounted troops. Usually having a barrel of 20” (508mm) or less.
  

CARTRIDGE

A single round of ammunition consisting of the case, primer, powder and one or more projectiles.
     

CARTRIDGE, CENTERFIRE

Any cartridge intended for use in rifles, pistols, and revolvers that has its primer central to the axis at the head of the case. 

Note: Most cartridges, including shotshells, are centerfire, with the exception of .17 and .22 caliber rimfire ammunition. The rear end of a centerfire cartridge has a primer in its center, hence “centerfire”.
     

CARTRIDGE, MAGNUM

Any cartridge or shotshell that is larger, contains more shot or produces a higher velocity than standard cartridges or shotshells of a given caliber or gauge. I.e., .44 Remington Magnum.
     

CARTRIDGE, RIMFIRE

A cartridge whose primer is contained in the rim of the case, which is also the part that's hit by the striker of the firearm.
     

CARTRIDGE, SMALL BORE 

A general term that refers to rimfire cartridges. Normally .22 caliber ammunition used for target shooting, plinking, and small-game hunting. Includes centerfire cartridges, such as the .223 remington, and rimfire cartridges, such as the .22 LR.
  

CHAMBER

In a rifle, pistol or shotgun, it is the part of the barrel that accepts the ammunition. In a revolver, it refers to the holes in the cylinder where the cartridges are loaded.
  

CHOKE

The constriction at the end of a shotgun barrel that controls shot dispersion. Chokes typically are cylinder, improved cylinder, modified, improved modified and full. 

Note: A cylinder choke produces a very wide shot dispersion, whereas a full choke will provide a much tighter shot pattern. Different chokes are used for skeet, trap and sporting clays. In hunting, the type of game and conditions will determine choke type.
  

CHOKE TUBES

Interchangeable threaded cylinders having different choke diameters (e.g. modified, full) that screw into the muzzle of a shotgun to allow for different shot patterns.

See also CHOKE.

  

CLIP

A small, thin, generally vaguely U-shaped piece of stamped metal that hosts ammunition for quick reloading, typically in military issue bolt-action rifles and early semi-automatic rifles and pistols manufactured in the first half of the 20th Century; clips were generally used with the gun bolt open, by inserting them in the open ejection window so that they would load the internal magazine in a single movement. Most rifles then required the empty clip to be removed before the bolt could be locked back and the gun could be ready to fire, although the U.S. M1 Garand rifle held it and ejected it once out of ammunition. Clips are currently − although seldom − used for the fast reload of detachable magazines. The term has since become a misnomer for detachable magazines.

See also MAGAZINE.
  

COCK (to)

The action of placing the hammer, or striker, in the loaded position, ready to fire. 

  

CONTROLLED PAIR

Combat shooting term for two fast aimed shots delivered in rapid succession.

  

CYLINDER

The round, rotatable part of a revolver that contains the cartridge chambers.




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D

  
DECOCK
The process by which the hammer is safely lowered to the nonfiring position.
  
DERRINGER

A generic term referring to many variations of pocket-sized pistols. The name comes from the pistol’s original designer, Henry Derringer.

Note: According to the American Derringer Company, Henry Deringer’s name is spelled with one ’R. ’ The proper spelling of Derringer firearms is with two ’R ’s.
  

DISCHARGE

To cause a firearm to fire.

  

DOUBLE-ACTION-ONLY (DAO)

A firing action where the hammer is cycled and the gun fired by a single pull of the trigger. The hammer returns to the down position after each shot and must repeat the entire cycle for every shot.
  

DOUBLE BARREL

Two barrels on a firearm mounted to one frame. The barrels can be vertically (over-under) or horizontally (side-by-side) aligned.

  

DOUBLE TAPS

Generic term for two fast shots on a target. More specifically, the "Double Tap" is that shooting technique that consists of firing two consecutive rounds at a single target at high speed − so high, in fact, that the second shot is fired before the spent case ejected after the first one has even touched the ground.

  

DRILLED AND TAPPED

Drilling holes and tapping (threading) them for screws to install mounts for optics on a handgun.
  

DUM DUM 

See also BULLET, DUMDUM.

  

DUST COVER

That part of a semiautoʼs frame extending forward from the trigger guard area. In AR-15 rifles and carbines: a small spring-loaded, stamped sheet port that locks the ejection window when the rifle is not in use or when the weapon is carried through harsh terrains, to prevent dust, earth, water or other dangerous elements from entering.


E

  
EJECTION

The removal of a spent case, or of a cartridge (either fired or unfired), from the breech of a firearm by means of a mechanical ejector.


EJECTOR
That part of a semiauto that causes an empty caseing to be forcefully driven from the gun as part of the recoil cycle.
  

EXTRACTION

The withdrawal of a cartridge (fired or unfired) from the chamber of a firearm by means of a mechanical extractor.

  

EXTRACTOR

That part of the slide of a semi-automatic pistol, or of the bolt in a rifle, carbine, or shotgun, that grasps the rim of a cartridge to withdraw it from the chamber.



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