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.

D

DAMASCUS BARREL

A barrel formed by twisting or braiding together steel and iron wires or bars. The resulting cable is then wound around a mandrel and forged into a barrel tube. Sometimes called a Laminated Barrel.

Also Known As: Laminated Barrel


DATUM

A reference plane, point or diameter that provides a base for calculations and measurements.


DEAD BLOW ACTION

A blow back action that utilizes a sliding weight, usually made of a dense material such as tungsten, in conjunction with the breechblock to counteract the effect of the breechblock inertia and retard the cyclic rebound rate of the breech block.


DECAPPER

A tool used to remove primers from cartridge cases or shells.


DEFINITIVE PROOF CARTRIDGE

A cartridge loaded to specific pressures higher than service loads. Used only for testing assembled firearms or elements of firearms which contain the primary firing pressure.

Also Known As: Proof Load


DEFLAGRATION

A rapid combustion reaction which is propagated at a sub-sonic rate by heat transfer into the reacting material. This reaction is accompanied by a vigorous evolution of heat and flame. The flow of reaction products is in the direction opposite that of the combustion propagation (unlike DETONATION). Deflagration is usually dependent upon having fuel and oxidizing agent in very close contact, either from having the fuel as a finely divided mixture with the oxidant, or by combining the two in the same chemical compound or mixture. Deflagration exhibits a dependence upon the surrounding gas pressure.


DEFLECTION

The variation in the normal flight path of a projectile caused by external influences.


DEFLECTOR

A device mounted on the receiver or frame of a firearm to change the direction of an ejected case.


DELAYED BLOWBACK ACTION

An action in which a mechanical means in conjunction with bolt mass is utilized to gain additional delay prior to bolt opening. Also called Retarded Blowback.

Also Known As: Retarded Blowback


DELAYED FIRE

Any delay in firing of an abnormal duration. This implies that firing does eventually occur.

Also Known As: Hangfire


DEMI-BLOCK

A type of double barrel construction in which the two barrels are fastened together.


DENT REMOVER

A gunsmithing tool used to remove dents from shotgun barrels. Also called Dent Raiser.

Also Known As: Dent Remover, Dent Raiser


DERRINGER

A generic term applied to many variations of small one-or two-shot pistols, using both percussion caps and cartridges. The original designer, Henry Deringer, spelled his name Deringer, not Derringer.


DESIGNATION – METRIC CARTRIDGE

Most foreign and some American commercial cartridges are identified by their nominal bullet diameter and cartridge case length, both of which are given in millimeters-e.g., 8x57, 7x57, 6.5x54mm.


DETENT

Indentation used as a stop for a spring-load lock.


DETONATION

An extremely rapid exothermic decomposition reaction which proceeds at a rate greater than the speed of sound within the reacting material (unlike DEFLAGRATION). The normal mode of initiation is shock (such as a blasting cap or high level mechanical shock), or from initial combustion which, due to peculiarities of confinement or other circumstances accelerates to such a degree that a shock wave is formed. Behind the shock wave is a reaction zone where material is converted to gaseous products at high temperature and pressure. The flow of the reaction is in the same direction as the propagation.


DEWAT

An acronym for DEactivated WAr Trophy.


DISCHARGE

To cause a firearm to fire.


DISCONNECTOR

A device intended to disengage the sear from the trigger. 1.) In a manually operated firearm, it is intended to prevent firing without pulling the trigger. 2.) In a semiautomatic firearm, it is intended to prevent full automatic firing. 3. A device that prevents out-of-battery firing.


DISINTEGRATING BULLET

Bullet that breaks into small pieces in flight or upon impact with the target.

Also Known As: Frangible


DISINTEGRATING PROJECTILE

A projectile that breaks up after leaving the muzzle and before it hits the target.


DISJUNCTOR

An electronic pulse forming device used in measuring projectile velocities.


DISPERSION

The greatest distance between any two bullet holes on a target, normally measured center-to-center.


DOLL’S HEAD

A usually round extension at the top of the barrel or rib of a shotgun which fits into a matching hole in the top of the standing breech.


DOMINANT EYE, MASTER EYE

The eye that controls both eyes when pointing toward or picking out an object.


DOUBLE ACTION

A firing mechanism in which the trigger serves the dual purpose of cocking and then releasing the firing mechanism - either hammer or striker. Double action firearms can be manually cocked similar to single action mode. For differentiation, see Single Action and Double Action Only.


DOUBLE ACTION ONLY

A firing mechanism in which the trigger serves the dual purpose of cocking and then releasing the firing mechanism - either hammer or striker. Double action only (DAO) firearms cannot be manually cocked to emulate single action mode. For differentiation, see Single Action and Double Action.


DOUBLE ACTION PISTOL

A pistol mechanism in which a single pull of the trigger cocks and releases the hammer.


DOUBLE ACTION REVOLVER

A type of revolver in which the rotation of the cylinder, cocking and firing are performed by a single pull of the trigger. Most Double Action revolvers can also be fired in the single action mode by manually cocking the hammer.


DOUBLE BARREL SHOTGUN

A shotgun with two barrels adjacent to each other in the horizontal plane (See Side-by Side). If arranged vertically, it is usually termed an “over/under” shotgun.


DOUBLE BASE POWDER

A propellant composed of colloided nitrocellulose and nitroglycerin as its base as opposed to single base powder which has colloided nitrocellulose only as its base material. The percentage of nitroglycerin added ranges from a low of 3% to a high of 39%.


DOUBLE PULL TRIGGER (2 STAGE)

A trigger which has two distinctive pull characteristics. The first or take-up stage is usually long and light in pull force; the second stage having a short but distinct increase in the pull force required to discharge the firearm.


DOUBLE SET TRIGGER

An arrangement of two triggers in which the actuation of one trigger presets the second resulting in a light trigger pull of the latter.


DOUBLE TRIGGER

A term used for firearms having two barrels and a separate trigger for the discharge of each. This term does not apply to firearms with double set triggers.


DOUBLE-BARREL

Two barrels in a firearm mounted to one frame. Can be vertically (“over-under”)or horizontally (“side-by-side”) aligned.


DOUBLE-GUN

A two-barrel firearm, usually side by side. Also known as Double Barrel or Double.

Also Known As: Double-Barrel, Double


DOUBLING

Simultaneous discharge of both barrels of a double-gun with a single pull of the trigger.


DOUGHNUT PATTERN

A pattern whose central area has few or no pellet hits.


DRAM EQUIVALENT

See "What does "dram equivalent" mean on shotgun ammunition (saami.org/faqs/#dram-equivalent-ammunition)


DRAW MARK

1. Ammunition - a longitudinal scratch on a cartridge case caused by foreign material on either the draw punch or die during fabrication. 2. Arms: See Witness Mark.


DRILLING

A three-barreled long gun in which a combination of smoothbore and rifled barrels is used.


DROP SAFETY

A passive safety mechanism that prevents unintentional firing when the firearm is dropped.


DROP SHOT

Lead shot containing less than 0.5% alloying metal. Also called Soft Shot.

Also Known As: Soft Shot


DROPPED PRIMER

One that is separated completely from the cartridge or shotshell after firing without obvious distortion of the primer pocket and head.


DRY FIRE

The practice of "firing" a firearm without the use of live ammunition.

Also Known As: Dry Firing


DUMDUM BULLET

An obsolete term referring to an expanding bullet manufactured at the British Arsenal in Dumdum, India around 1900.


DUMMY CARTRIDGE

An inert cartridge which cannot be fired under any circumstances. In America, an inert cartridge for gun functioning is usually black oxidized and may or may not have holes in the side wall of the case. An inert cartridge for display may be natural colored and should have a hole in the primer cup with holes in the side wall of the case optional.


DUPLEX LOAD

1. A cartridge case containing two projectiles with a single powder charge. 2. A cartridge case containing a single projectile with two types of powder.


DUST COVER

1). A cover over the ejection port of a firearm to reduce the possibility of the entrance of foreign matter into the action. 2). The forward part of a pistol frame which protects the recoil spring.


DUST SHOT

Lead shot having a nominal diameter of .040” or smaller.