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.

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ACCELERATOR

A device found in some semiautomatic firearms that, through mechanical advantage or spring energy, transfers kinetic energy from one part of the mechanism to another with the resultant speeding up of the action.


ACCURACY

In firearms using single projectiles at a given distance, is the measure of the dispersion of the group of projectiles fired. The optimum would be one hole no larger in diameter than a single projectile.

Also Known As: Mean Radius


ACCURACY LIFE

An estimated, or empirically determined, number of rounds that can be fired in a particular gun, of a particular caliber, before it fails to meet a particular accuracy specification. Wide variations may occur due to caliber, ammunition characteristics, firing schedules, maintenance and firearm design.


ACCURIZE

The act of subjecting a firearm and its components to special fitting and operations with the goal of optimizing accuracy.


ACTION

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


ACTION BAR FLATS

Formed or machined surfaces on the action bars which control or actuate, through cams or blocks, the movement of other parts of the firearm as the bars move in a reciprocal motion.

Also Known As: Action Bar(s)


ACTION BAR(S)

A member or members, which are used to connect and, thus transmit the movement of the forearm or gas system to the breech block. In many designs, the movement of the action bars controls or actuates other parts of the mechanism.

Also Known As: Action Bar Flats


ACTUATOR

Part of the firing mechanism in certain automatic firearms, such as trigger actuator, which slides forward and back in preparing each round to be fired.


ADJUSTABLE SIGHT

Usually taken to mean a rear sight that is adjustable for windage or elevation or both. However, adjustable front sights are sometimes used on target firearms.


ADJUSTABLE TRIGGER

Any trigger mechanism which has features that can be adjusted.


AIM

The act of aligning a firearm on a target.


AIMING POINT

A point on the target upon which the firearm is aimed.


AIR GAUGE

A pneumatic device for measuring diameters.


AIR GUN

A gun that uses compressed air or gas (e.g. carbon dioxide) to propel a projectile. Technical standards for air guns do not fall under the purview of the Sporting Arms and Manufacturers' Institute.

Also Known As: Air Rifle


AIR PISTOL

A handgun with the same principle of operation as an air gun. Also called Pellet Pistol. See Air Gun.

Also Known As: Pellet Pistol

Related Terms: AIR GUN


AIR RESISTANCE

The resistance of air to the passage of a projectile in flight.


AIR SPACE

The volume in a loaded cartridge or shotshell not occupied by the propellant or the bullet, wads or shot. Sometimes called Ullage.

Also Known As: Ullage


AIR SPIRAL

The term used to describe the corkscrew-like flight path of a bullet.


ALTITUDE EFFECT

The effect on velocity and, therefore, trajectory and shotshell pattern caused by changes in atmospheric density due to altitude.


AMMUNITION

One or more loaded cartridges consisting of a primed case, propellant and with or without one or more projectiles.


AMMUNITION CODE NUMBER

A code number and/or letter(s) usually found on the carton that identifies a particular quantity of ammunition for its manufacturer.


AMMUNITION COLOR CODE

A method of distinguishing various gauges of shotshells and types of metallic ammunition by color or plating.


AMMUNITION LOT

A continuously produced batch of ammunition uniquely identified by a code. Lot size is determined by the manufacturer as part of their manufacturing process.


ANGLE OF DEPARTURE

The angle formed between a horizontal line and the center line of the bore at the moment the projectile leaves the muzzle of the gun.


ANGLE OF ELEVATION

The vertical angle formed between the line of sight to the target and the axis of the barrel bore.


ANNULUS

The ring-like space between the top of the primer and the primer pocket or battery cup on the base of a cartridge.


ANSON FASTENING FORE-END

A fastening method of the fore-end of double barreled shotguns which utilizes a spring loaded bolt that extends beyond the tip of the fore-end. A British term.


ANTIMONY

A metallic element used to alloy lead to increase hardness. Symbol Sb.


ANVIL

An internal metal component in a cartridge primer assembly against which the priming mixture is pinched by the firing-pin blow. See Primer.


APERTURE SIGHT

A form of metallic sight, front or rear, containing and aperture or disc with a hole. Also called Peep Sight, or Receiver Sight (if mounted on receiver). See Sight Aperture.

Also Known As: Peep Sight, Receiver Sight


ARM

1. To charge or load a firearm. 2. Contraction of “firearm.”


ARMOR PIERCING

1) A projectile designed to penetrate armor.
2) A regulatory term applied to projectiles based solely on their composition and construction details, regardless of actual ability to penetrate armor.


AUTOMATIC ACTION

A firearm design that continuously feeds cartridges, fires and ejects cartridge cases as long as the trigger is fully depressed and there are cartridges available in the feed system. Actuation of the mechanism may be from an internal power source such as gas pressure or recoil, or external power source, such as electricity.

Also Known As: Auto, Full Auto, Machine Gun


AUTOMATIC EJECTOR

A device in break-open firearms which expels fired cases when the action is opened.


AUTOMATIC FEED MECHANISM

A system for reloading a firearm utilizing some of the energy realized from firing a cartridge.


AUTOMATIC PISTOL

A common but improperly used term applied to autoloading pistols in use today. Most current “automatic” pistols are truly semiautomatic in action only. See Semiautomatic.

Also Known As: Automatic Fire


AUTOMATIC RIFLE

A fully automatic shoulder firearm that starts firing when the trigger is pulled and continues until the trigger is released or ammunition is exhausted. The term should not be used in conjunction with semiautomatic firearms. See Semiautomatic.

Also Known As: Automatic Fire


AUTOMATIC SAFETY

A safety device on some firearms intended to return to the On position when the action is opened.


AUXILIARY CHAMBER, AUXILIARY CARTRIDGE

An adapter that, when installed in a gun chamber for which it was designed, permits a smaller cartridge to be fired in the gun.


AVERAGE PRESSURE

The arithmetic mean of pressure measurements for a number of rounds in a single test.