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.
G
GAIN TWIST
Barrel rifling in which the rate of twist is faster at the muzzle than at the chamber end.
GAS CHECK
1. A metallic cup attached to the base of some lead alloy bullets. 2. An obturating cup used under the piston in crusher pressure testing.
GAS CHECK BULLET
A lead alloy bullet with a cup pressed over the heel. Usually copper or gilding metal.
GAS CUTTING
An erosive effect in a firearm caused by the high velocity, high temperature propellant gases.
GAS OPERATED ACTION
An automatic or semiautomatic type firearm in which the propellant gases are used to unlock the breech bolt and then to complete the cycle of extraction and ejection. This is accomplished usually in conjunction with a spring which returns the operating parts to battery.
Also Known As: Gas Operated
GAS PISTON
The component in a gas-operated firearm upon which the propellant combustion gas impinge to operate the action.
GAS PORT
An opening in the wall of a barrel or chamber to allow the redirection of propellant gas. Usually associated with gas-operated actions or other mechanisms.
Also Known As: Ported Barrel, Gas Orifice
GAS VENT
1. Any hole in the action of a firearm to allow the escape of gases from the breech. 2. A hole in the gas cylinder of a firearm to bleed off gas. 3. Ammunition: See Flash Hole. 4. See Barrel Vent.
Related Terms: BARREL VENT, FLASH HOLE
GAUGE
1. A term used in the identification of most shotgun bores. (410 bore is an exception.) It is related to the number of bore diameter lead balls weighing one pound. 2. An instrument for measuring or testing a parameter.
GILDING METAL
A copper alloy with a nominal composition of 95 percent copper and 5 percent zinc. “Gilding Metal” is the trade name for the Copper Development Association, Inc. Alloy C21000. It is extensively, but not exclusively used in the manufacture of bullet jackets. See also “Commercial Bronze.”
GLASS BEDDING
The application of a mixture of fiberglass and resin between the action and/or barrel and stock.
GLOBE FRONT SIGHT
A form of front sight usually used on target rifles generally cylindrical in shape and arranged to accept various inserts containing either rings or posts.
GRAIN
1. A unit of weight (avoirdupois), 7000 grains per pound. The grain unit is commonly used in American and English ammunition practice to measure the weight of components. 2. A term sometimes applied to a single particle of propellant powder. More properly called a kernel or granule.
GRIP
1. In handguns, the handle. 2. In shoulder arms, that portion of the stock to the rear of the trigger.
GRIP ADAPTER
A filler piece attached to the front of the grip of a firearm.
GRIP SAFETY
An auxiliary device on the grip of some handguns which is intended to prevent firing until depressed.
GROOVE DIAMETER
The major diameter in a barrel which is the diameter of a circle circumscribed by the bottom of the grooves in a rifled barrel.
GROUP
A series of consecutive shots fired at the same aiming point without changing the sight adjustments of the firearm.
GROUP SIZE
The determination of the statistics of a particular group. Examples of measurements include Extreme Spread, Mean Radius, Vertical and Horizontal Extreme Spread, to name a few.
Also Known As: Accuracy
GUARD SCREW
A screw that extends from the trigger guard into and through the stock.
GUN COTTON
Nitrated cellulose (either cotton linters, wood pulp or a mixture of the two) which is used for the manufacture of smokeless propellant. Chemical name – nitrocellulose.
GUN POWDER
A commonly used term for cartridge and muzzle loading propellant.
GUN ROOM
A room that is maintained for the purpose of keeping guns in storage, on display, or for repair.