Glossary

The Glossary of Industry terms has been compiled by SAAMI’s Technical Committee to facilitate technical interchanges between members of that committee. It is not intended to provide legal definitions of the terms included, and, in light of further experience, the definitions of these terms may change. It is not intended to be comprehensive since it does not cover the full range of the diversity of the sporting arms and ammunition industry’s products. It is, in other words, a working draft that, it is hoped, may be useful in addressing certain technical matters frequently considered by the Technical Committee and is subject to further change and refinement.

It was the committee’s decision that ONLY industry terms would be included which are unique to the firearms and ammunition industry directly. Optical terms have been omitted for the most part. Common metallurgical terms were not included because they are not unique to the industry. Where there is a common term with a usage unique to our industry, it has, however, been included.

B

BACK BORE

A shotgun, chambered for a specified gauge, whose barrel bore diameter is greater than the nominal specified for that gauge, but does not exceed SAAMI maximum.


BACK STRAP

The exposed metal strip at the rear of a pistol or revolver grip.

Also Known As: Strap


BACKSTOP

A structure intended to safely stop a fired bullet or other projectile(s).


BACKTHRUST

The force exerted on the breech block by the head of the cartridge case during propellant burn.

Also Known As: Bolt Thrust


BALL AMMUNITION

A term generally used by the military for a cartridge with a full metal jacket or solid metal projectile (bullet).

Also Known As: Ball Cartridge


BALL POWDER

Ball Powder is a registered trademark for propellant, owned by General Dynamics Ordnance and Tactical Systems, Inc. often misapplied to spherical propellants or flattened spherical propellants offered by other manufacturer.


BALL SCREW

A pointed, spiral piece of metal secured at the end of a ramrod and used to remove a lead ball or patch from a muzzle loading gun.


BALLED SHOT

The fusing together of several pellets in a shotshell load, usually caused by hot propellant gases leaking past the wadding and fusing the shot while the shot is still in the barrel. See Fused Shot.


BALLISTIC COEFFICIENT

An index of the manner in which a particular projectile decelerates in free flight expressed mathematically as: c = w/id2 where: c = ballistic coefficient, w = mass, in pounds, i = coefficient of form (a.k.a. form factor), d = bullet diameter, in inches. Represents the bullet’s ability to overcome the air resistance in flight.


BALLISTIC TABLE

A descriptive and performance data sheet on ammunition. Information usually includes: bullet weight and type; muzzle velocity and energy; velocity; energy and trajectory data at various ranges.


BALLISTICS

The science of projectiles in motion. Usually divided into three parts: 1.) Interior Ballistics, which studies the projectile's movement inside the barrel of a firearm; 2.) Exterior Ballistics, which studies the projectile's movement between the muzzle and the target; and 3.) Terminal Ballistics, which studies the projectile's movement in the target.


BAR SIGHT

A rear sight that incorporates a high visibility, typically horizontal, bar immediately below the rear sight notch. Usually used in conjunction with a high visibility dot front sight.


BARREL

Firearm component through which a projectile travels. May be rifled or smooth bore.


BARREL ASSEMBLY

A barrel of a firearm, either fixed or interchangeable, that has been fitted with necessary parts so that it may be assembled to the remainder of the firearm.


BARREL BAND

A strip or strips of metal that encircle and hold the barrel and stock, fore-end, magazine or other accessories together.


BARREL BLANK

An unfinished barrel in any state of completion.

Also Known As: Blank


BARREL CHANNEL

A groove in a rifle stock or fore-end where the barrel fits in the assembled position.


BARREL DIAMETER

The outside dimension of a barrel at any given point.


BARREL EROSION

The wearing or physical deterioration of the bore or chamber of a firearm caused by hot propellant gases or projectile passage.


BARREL EXTENSION

A metal projection which extends rearward from the breech end of a barrel into which the breech locks while the firearm is in battery or firing position.


BARREL GUIDE

A ring shaped attachment on the barrel of many shotguns which encircles the magazine tube. Sometimes called Magazine Tube Bracket.

Also Known As: Magazine Tube Bracket


BARREL JACKET

A tube that surrounds the barrel.


BARREL LENGTH

On shoulder arms and most handguns the distance between the muzzle of the barrel and the face of the breech block or bolt. On revolvers, it is the overall length of the barrel only, including the portion within the frame.


BARREL LIFE

The total number of rounds fired in a barrel before it becomes unserviceable.


BARREL LUG

A general term for any projection extending at right angles to the barrel.


BARREL OBSTRUCTION

Also called bore obstruction. A foreign object or material in the bore of a barrel which prevents unhindered passage of projectile(s) when fired.


BARREL PRESSURE

The pressure in a barrel developed by propelling gases when a cartridge is fired.


BARREL REFLECTOR

Also called bore reflector. A device with a mirror for examining the bore and chamber of a barrel.


BARREL RELINING

The replacement of the interior surface of a bore by inserting and fastening a tube. Usually refers to rifled barrels.

Also Known As: Barrel Liner


BARREL SHANK

The breech end of the barrel that fits into the action or receiver.


BARREL SLEEVING

This term usually refers to shotgun barrels. See Barrel Relining.

Related Terms: BARREL RELINING


BARREL STEP

An abrupt change in external barrel contour.


BARREL STRIKING (DRAWFILING)

The longitudinal hand filing of a barrel on its exterior surface to produce a smooth finish.


BARREL THREADS

1. Threads found on the breech of the barrel, used to screw some barrels into the frame or receiver of the firearm. 2. Threads found on the muzzle end of the barrel, used to attach a muzzle device


BARREL TIME

The elapsed time from the contact of a firing-pin with a cartridge primer to the emergence of the projectile(s) from the muzzle of the firearm.

Also Known As: Ignition Barrel Time


BARREL VENT

An opening or series of openings or ports in a barrel, normally near the muzzle, through which gases pass prior to bullet exit. See Muzzle-Brake.


BARREL VIBRATION

The oscillations of a barrel as a result of firing.


BARREL WEAR

The gradual mechanical deterioration caused by use, i.e. firing, cleaning, etc. Also, see Barrel Erosion.

Related Terms: BARREL EROSION


BARREL WEIGHT

A separate weight attached to a regular barrel to change balance.


BARREL WHIP

The movement of the muzzle end of a barrel that occurs as the projectile leaves.


BARREL-CYLINDER GAP

The opening or clearance between barrel and cylinder in a revolver. See also Cylinder Gap.


BARRELED ACTION

The combination of barrel and receiver or frame together with the other parts of the mechanism by which a firearm is loaded, fired and unloaded.

Also Known As: Barreled Action


BASE WAD

A cylindrical component that is assembled into the head end of a shotshell.


BATTERY

The condition where the breech of the action is in proper position for firing.


BATTERY CUP

A component of a shotshell primer; a flanged metallic cup that contains and supports the primer cup and anvil.


BATTERY CUP PRIMER

1. A flanged metal cup having a flash hole at the bottom end. 2. An ignition component using a battery cup as a holder for the other elements, usually found in shotshells.


BAYONET LUG

A feature on a firearm designed to allow the mounting of a bayonet.


BB

The designation of spherical shot having a diameter of .180” used in shotshell loads. The term BB is also used to designate steel or lead air rifle shot of .175” diameter. Although the two definitions cause some confusion, they have coexisted for many years.


BB CAP

The abbreviation for Bulleted Breech Cap. The original design in 1845 was a percussion cap without a well defined head loaded with a 22 caliber ball. A rimfire cartridge designed for use in Flobert rifles for indoor use. Several variations followed.


BEAD SIGHT

A spherical sight typically used on shotgun barrels.


BEARING SURFACE

That portion of a bullet’s outer surface that comes into direct contact with the interior surface of the barrel bore when moving through the barrel.

Also Known As: Band


BEAVERTAIL FOREARM

A wider than normal, usually flattened, forward part of a two-piece stock.


BEAVERTAIL FORE-END

A wider than normal, usually flattened, forward part of a stock.


BEDDING

Refers to the fit or fitting of the metal parts of the barrel and receiver with the wood stock.


BEDDING CONTROL

1. An adjustable device, which is installed in the fore-end of a rifle stock to provide pressure on a barrel. 2. The pressure provided by the wood-to-metal fit.


BEDDING SCREW(S)

A form of Bedding Control using machine screw(s) to produce a pressure on the underside of the barrel.


BELTED CARTRIDGE

A cartridge with a case design having an enlarged band ahead of the extractor groove. This design was originally intended to headspace cartridges with an insufficient shoulder angle (i.e. 300 H&H Magnum, 375 H&H Magnum).

Also Known As: Belted Magnum, Belted Case


BENCHREST

A table specifically designed to eliminate as much human error as possible by supporting a rifle for competitive shooting or for sighting-in purposes.


BENCHREST RIFLE

A rifle designed for optimum accuracy while being shot from the shoulder and supported by a specifically designed table (rest).


BENCHREST STOCK

Generally, a large and heavy stock used exclusively for benchrest shooting.


BENT

A notch, usually in the hammer, in which the sear or trigger is held under tension of the mainspring until released by movement of the trigger or hammer. See Half Cock. See Full Cock.


BERDAN PRIMER

An ignition component consisting of a cup, explosive mixture and covering foil. The anvil is an integral part of the cartridge case head in the bottom center of the primer pocket. One or more flash holes are drilled or pierced through the bottom of the primer pocket into the propellant cavity of the base. Commonly found in European cartridges.


BIFURCATED LUMPS

A type of projection found mainly on top-break action gun designs. The bifurcated or divided projections are mounted on each side of the barrel (or lower barrel in over/under designs) and engage trunnions located on the receiver wall. This serves to reduce the overall height of the receiver-barrel assembly.


BIG BORE

A non-technical term generally referring any firearm using a centerfire rifle cartridge with a bullet .30” or larger in diameter.


BIG BORE CARTRIDGE

For target matches in the United States, cartridges utilizing bullets 0.300” in diameter or larger.


BILLIARD BALL EFFECT

The divergence of shot pellets caused by collisions of pellets in the shot string as it comes into contact with the target.


BIRD SHOT

A general term used to indicate any shot smaller than buckshot.


BIRD’S HEAD GRIP

A handgun grip that comes to a point in front, making it resemble a bird’s head.


BLACK POWDER

The earliest form of propellant, reputed to have been made by the Chinese or Hindus before the remote beginnings of history. First used for guns in the 13th century. It is a mechanical mixture of potassium or sodium nitrate (“saltpeter”), charcoal and sulfur.


BLADE SIGHT

Thin, flat projection used as the front sight on some firearms.

Also Known As: Front Sight Blade


BLANK CARTRIDGE

A cartridge loaded without a projectile designed to produce a loud noise. Often sealed at the mouth with a cardboard, plastic or fiber wad which is propelled from the muzzle with a dangerous force for a short distance when fired.

Also Known As: Blank


BLANK STOCK

A rough sawed piece of wood having the approximate external outline of a stock prior to final shaping.

Also Known As: Blank


BLANKED PRIMER

A fired primer cup in which the firing-pin indent has been punched out by internal gas pressure.


BLIND BOX MAGAZINE

A magazine having a permanently closed bottom. Loading and unloading are accomplished through the same opening.


BLOWBACK

A leakage of propellant gas rearward between the cartridge case and chamber wall.


BLOWBACK ACTION

An automatic or semiautomatic action that utilizes the expanding gases of the ignited propellant powder to drive the breechblock action rearward. In other firearms the breechblock holds the breech closed under the force of the recoil spring, no mechanical locking system being employed. In a blowback action, the inertia of the movable parts is such that the bullet leaves the muzzle after discharge before the breechblock moves rearward.


BLOW-BY

A leakage of propellant gas forward past the bullet in the barrel.


BLOW-FORWARD, BLOW-FORWARD ACTION

A self-loading action in which the breech block is stationary and the barrel moves forward to cycle the action.


BLOWN PATTERN

A pellet distribution (pattern) with an unusually low percentage of pellets and/or of erratic distribution. Depending on its overall shape and pattern distribution, may also be referred to as a Doughnut Pattern.


BLOWN PRIMER

A primer that is separated completely from the cartridge or shotshell after firing due to severe expansion of the primer pocket and head.


BLUING

The chemical oxidation to color ferrous metal parts various shades of blue or black.

Also Known As: Blueing, Black Oxide


BLUING TANKS

Tanks used to contain the solutions used for bluing of firearms.

Also Known As: Bluing Tank


BOAT-TAIL BULLET

A specific design of bullet having a tapered or truncated conical base.


BODY (CASE)

1. The portion of the cartridge case which contains the propellant. 2. Shotshell - the tubular section that contains the propellant, wads and shot charge (if present).


BOLT ACTION

An action in which the bolt is in line with the bore at all times; manually reciprocated using a handle attached to the bolt to load, unload and cock. There are two principle types of bolt actions: the turn bolt and the straight pull type.


BOLT GUIDES

Grooves or ridges on either bolt or receiver intended to maintain alignment or prevent over-rotation.


BOLT HANDLE

A protrusion from the bolt, usually at right angles from the axis of the bolt, which is used to manually actuate the mechanism.


BOLT HANDLE BENDING JIG

A mechanism of two or more pieces which is used in the alteration of bolt handles.


BOLT HEAD

The forward end of the bolt containing the bolt face or breech face.


BOLT LOCKING LUG(S)

The protrusion or protrusions from the surface of the bolt body which lock into mating recesses in the receiver, barrel or barrel extension to resist rearward thrust of the chamber pressure.

Also Known As: Locking Lug, Bolt Lug


BOLT RACEWAY

Longitudinal grooves in the receiver in which the bolt lugs or other projections travel.


BOLT RELEASE

1. A device which allows the bolt to be removed from the firearm. 2. A device which allows the bolt to move into battery from the "hold open" position.


BOLT SLEEVE

A component at the rear end of the bolt which guides the firing-pin and supports the firing-pin spring in bolt action rifles. Also called bolt plug.

Also Known As: Bolt Plug


BOLT STOP

A device which is intended to retain the bolt in the firearm during normal operation.


BOLT THROW

The distance the bolt travels from “fully open” to “fully closed” position.


BOOT

1. A protective device used on the buttstock of a firearm during test firing 2.A type of recoil pad.


BORE

The interior of a barrel forward of the chamber.


BORE AXIS

A theoretical line through the center of the bore.

Also Known As: Axis of Bore, Line of Bore


BORE BRUSH

A brush used to clean the interior surface of the barrel of a firearm.


BORE CASTING

The pouring of a special alloy or material that has a low melting point and exceptional dimensional stability into the bore or chamber of a firearm. The cast is used to study physical characteristics of the bore.


BORE CONSTRICTION

A reduction in the internal diameter of a firearm bore.


BORE DIAMETER

1. Rifled barrels: the minor interior diameter of a barrel which is the diameter of a circle formed by the tops of the lands. 2. Shotguns or muskets, the interior dimension of the barrel forward of the chamber but before any restrictive choke or expanded muzzle.

Also Known As: Land Diameter


BORE SIGHTING

A method of aligning a barrel on a target by aiming through the bore. May be part of the sight alignment procedure.


BORESCOPE

An illuminated, optical device for examining the interior of the bore of a firearm.


BOTTLENECK CARTRIDGE

A cartridge case having a main body diameter and a distinct angular shoulder stepping down to a smaller diameter at the neck portion of the case.

Also Known As: Bottleneck Case


BOX LOCK ACTION

An action commonly used in break-open firearms in which the hammer and hammer springs are located within the frame and are self-cocking.

Also Known As: Boxlock Action


BOX MAGAZINE

A rectangular receptacle attached to or inserted into a firearm that holds cartridges stacked on top of one another ready for feeding into the chamber.


BOXER PRIMER, AMERICAN PRIMER

An ignition component consisting of a cup, explosive mixture, anvil and covering foil or disc which together form the completed primer ready for assembly into the primer pocket of a cartridge case. One central flash hole is pierced through the bottom of the primer pocket into the propellant cavity of the case. Used in modern commercial centerfire ammunition made in Canada and the United States.


BREECH

The end of the barrel where the ignition of the propellant takes place.


BREECH BOLT

The locking and cartridge head supporting mechanism of a firearm that operates in line with the axis of the bore.

Also Known As: Bolt


BREECH BORE SIGHT

A fixture having a small centrally located aperture that fits into a firearm chamber. Used in conjunction with a similar device that fits into the muzzle to establish the axis of the bore.


BREECH FACE

That part of the action which is against the head of the cartridge case or shotshell when in battery.

Also Known As: Bolt Face, Breech Block Face, Breech Bolt Face


BREECH PLUG

In percussion or flintlock firearms, the metal part that is threaded into the breech end of the barrel.


BREECH STANDING

That part of the frame of a revolver or break-open firearm which supports the head of the cartridge when it is fired.


BREECHBLOCK

A mechanism which does not operate in line with the axis of the bore, and which is intended to support, properly, the head of the cartridge.


BREECHING SPACE

A misnomer. Commonly confused with headspace.


BRENNEKE SLUG

A formed rifled slug with a wad assembly attached to its base by a screw for use in shotguns.


BRIDGE

A component of a firearm action which usually straddles other parts and acts as a guide or support.


BRIDGING POWDER

The wedging action of powder in the feed tube of a cartridge loading device causing stoppage of normal flow.


BRISANCE

A term describing the shattering power of high explosives.


BROACH RIFLING

The process of forming spiral rifling grooves in the barrel of a firearm by a tool having a series of cutting edges each slightly larger than the preceding.

Also Known As: Barrel Broaching


BROWNING

A chemical oxidation process to color metallic parts of a firearm a brownish black shade.


BUCKHORN SIGHT

A rear sight for hunting rifles that has the V notch at the bottom of an almost completely closed “U.”


BUCKSHOT

Lead pellets ranging in size from .24” to .36” diameter normally loaded in shotshells.


BUFFER

1. In a firearm, any part intended to absorb shock, reduce impact or check recoil. 2. In a shotshell, any material added to the shot to prevent deformation during firing.


BULGE CHAMBER

A chamber with an abnormal enlargement.


BULGED BARREL

A localized enlargement of the barrel bore typically caused by the firing of a round into an obstruction within the barrel. If the bulge is circumferential: See Ring Bulge.


BULL

A slang term for Bullseye of Target. See Bullseye.


BULL BARREL

A firearm built with an extra-thick, heavy barrel, used primarily for target shooting or varmint hunting.

Also Known As: Bull Gun


BULL PUP

A shoulder-fired firearm in which the action is behind the fire control system.


BULLET

A non-spherical projectile for use in a rifled barrel and sometimes contained within a sabot.


BULLET CASTING

A process for making lead bullets by pouring molten metal into a mold.


BULLET CORE

The inner section of a jacketed bullet, usually lead.

Also Known As: Core


BULLET CREEP

The movement of a bullet out of the cartridge case due to the recoil of the firearm (and the inertia of the bullet) when firing another cartridge in the firearm.

Also Known As: Bullet Jump, Bullet Popping


BULLET DIAMETER

The maximum dimension across the largest cylindrical section of a bullet.


BULLET DROP

1. The difference between the bullet’s vertical position relative to the bore axis at any given point in its flight.

2. In ballistic performance tables, the deviation from the line-of-sight and the bullet’s position at any given point in its flight. In this usage, knowledge of the distance at which the sighting device is adjusted to yield a deviation of *zero* (“sighting-in” range) must be known.

Also Known As: Projectile Drop


BULLET ENGRAVING

1. The grooves cut into a bullet by barrel rifling. 2. The forming of grooves in a bullet by the barrel rifling.


BULLET JACKET

A separate layer in a bullet's construction on at least the portion of the bullet engaging the firearm's rifling.


BULLET JUMP

The distance that a bullet must travel from its position at rest in the cartridge case to its initial engagement of the rifling.

Also Known As: Free Travel


BULLET LUBRICATOR

The tool used to lubricate bullets.


BULLET MOLD

A split block of metal having one or more cavities into which molten lead is poured to form a bullet.


BULLET PENETRATION

That distance which a bullet travels into the target material.


BULLET PULL

The force required to extract a bullet from the case into which it was loaded.


BULLET PULLER

1. An instrument that measures the force required to extract a bullet from live ammunition. 2. A tool used to remove bullets from live ammunition.


BULLET SLIPPAGE OR STRIPPING

Slippage or stripping occurs if the bullet fails to engage the rifling properly.


BULLET SPIN OR ROTATION

The rotational motion imparted to the bullet by the rifling in the barrel.


BULLET SPINNER

A mechanical device used to detect the amount of eccentricity in a bullet between its rotational axis and the outer surface of the bullet.


BULLET SPLASH

The spatter and fragmentation of a bullet upon impacting a hard surface.


BULLET STABILIZATION

The principal to account for the steadiness of flight conferred upon an elongated projectile.


BULLET TIPPING

The instability of a bullet in flight in which the point of the bullet is not aligned with the direction of flight.

Also Known As: Tipping


BULLET TRAP

A device to safely stop a bullet in flight. Usually found in indoor ranges behind the target area.


BULLET UPSET

1. In Interior Ballistics: The change of bullet form due to chamber pressure. 2. In Exterior Ballistics: The expansion of a bullet upon impact with target.


BULLET WOBBLE

A characteristic caused by the eccentricity or imbalance of the bullet to the axis of the bore. See Yaw.


BULLET-PUSH

The force required to shorten a cartridge by pushing on the bullet.


BULLSEYE

In target shooting, the aiming point.


BUTT

1. Handguns: Bottom part of the grip. 2. Long Guns: Rear or shoulder end of the stock.


BUTT PLATE

A metal, rubber or composition covering to reinforce and protect the shoulder end of a firearm stock.


BUTT STOCK

The rear or butt end of the firearm which is normally placed against the shooter’s shoulder.


BUTTERKNIFE BOLT HANDLE

A flat, low profile, paddle-shaped bolt handle found on some rifles.


BUTTON RIFLING

A process wherein a hardened steel disc or button with a rifling cross section configuration is pushed or pulled through a drilled and reamed barrel so as to cold form the rifling grooves to the desired depth and twist.