This glossary hardly covers all firearms terms, but it does
list a few of those that are most misused in reportage and proposed
legislation. If no errors in terminology were made by the media or
by members of Congress, errors in perception by the general public
ACTION: The working mechanism of a firearm. Various types exist,
including single-shots, multi-barrels, revolvers, slide- or pump-
actions, lever-actions, bolt-actions, semi-automatics and
AIRGUN: Not a firearm but a gun that uses compressed air or CO2 to
propel a projectile. Examples: BB gun, pellet gun, CO2 gun.
AMMUNITION: This generally refers to the assembled components of
complete cartridges or rounds i.e., a case or shell holding a
primer, a charge of propellant (gunpowder) and a projectile
(bullets in the case of handguns and riflesžmultiple pellets or
single slugs in shotguns). Sometimes called "fixed ammunition" to
differentiate from components inserted separately in muzzleloaders.
ANTIQUE: By federal definition, a firearm manufactured prior to
1899 or a firearm for which ammunition is not generally available
or a firearm incapable of firing fixed ammunition.
ARMOR-PIERCING AMMUNITION: By federal definition, "a projectile or
projectile core which may be used in a handgun and which is
constructed entirely (excluding the presence of traces of other
substances) from one or a combination of tungsten alloys, steel,
iron, brass, bronze, beryllium copper, or depleted uranium. Such
term does not include shotgun shot required by . . . game
regulations for hunting purposes, a frangible projectile designed
for target shooting, a projectile which the Secretary finds is
primarily intended to be used for sporting purposes, or any other
projectile or projectile core which the Secretary finds is intended
to be used for industrial purposes, including a charge used in an
oil and gas well perforating device."
ASSAULT RIFLE: By U.S. Army definition, a selective-fire rifle
chambered for a cartridge of intermediate power. If applied to any
semi-automatic firearm regardless of its cosmetic similarity to a
true assault rifle, the term is incorrect.
ASSAULT WEAPON: Any weapon used in an assault (see WEAPON).
AUTOMATIC: A firearm designed to feed cartridges, fire them, eject
their empty cases and repeat this cycle as long as the trigger is
depressed and cartridges remain in the feed system. Examples:
machine guns, submachine guns, selective-fire rifles, including
true assault rifles.
AUTOMATIC PISTOL: A term used often to describe what is actually a
semi-automatic pistol. It is, technically, a misnomer but a near-
century of use has legitimized it, and its use confuses only the
BALL: Originally a spherical projectile, now generally a fully
jacketed bullet of cylindrical profile with round or pointed nose.
Most commonly used in military terminology.
BLACKPOWDER: The earliest type of firearms propellant that has
generally been replaced by smokeless powder except for use in
muzzleloaders and older breechloading guns that demand its lower
BLANK CARTRIDGE: A round loaded with blackpowder or a special
smokeless powder but lacking a projectile. Used mainly in starting
races, theatrical productions, troop exercises and in training
BOLT-ACTION: A gun mechanism activated by manual operation of the
breechblock that resembles a common door bolt.
BORE: The interior of a firearm's barrel excluding the chamber.
BRASS: A synonym for expended metallic cartridge cases.
BULLET: The projectile expelled from a gun. It is not synonymous
with cartridge. Bullets can be of many materials, shapes, weights
and constructions such as solid lead, lead with a jacket of harder
metal, round-nosed, flat-nosed, hollow-pointed, etc.
CALIBER: The nominal diameter of a projectile of a rifled firearm
or the diameter between lands in a rifled barrel. In this country,
usually expressed in hundreds of an inch; in Great Britain in
thousandths; in Europe and elsewhere in millimeters.
CARBINE: A rifle with a relatively short barrel. Any rifle or
carbine with a barrel less than 16" long must be registered with
the Bureau of Alcohol, Tobacco and Firearms. Shotguns with barrels
less than 18" long fall into the same category.
CARTRIDGE: A single, complete round of ammunition.
CASE, CASING: The envelope (container) of a cartridge. For rifles
and handguns it is usually of brass or other metal; for shotguns it
is usually of paper or plastic with a metal head and is more often
called a "shell."
CENTER-FIRE: A cartridge with its primer located in the center of
the base of the case.
CHAMBER: The rear part of the barrel that is formed to accept the
cartridge to be fired. A revolver employs a multi-chambered
rotating cylinder separated from the stationary barrel.
CHOKE: A constriction at or near the muzzle of a shotgun barrel
that affects shot dispersion.
CLIP: A device for holding a group of cartridges. Semantic wars
have been fought over the word, with some insisting it is not a
synonym for "detachable magazine." For 80 years, however, it has
been so used by manufacturers and the military. There is no
argument that it can also mean a separate device for holding and
transferring a group of cartridges to a fixed or detachable
magazine or as a device inserted with cartridges into the mechanism
of a firearm becoming, in effect, part of that mechanism.
COP-KILLER BULLET: An inflammatory phrase having neither historical
basis nor legal or technical meanings.
CYLINDER: The drum of a revolver that contains the chambers for the
DERRINGER: A small single-shot or multi-barrelled (rarely more than
two) pocket pistol.
DETONATE: To explode with great violence. It is generally
associated with high explosives e.g. TNT, dynamite, etc., and not
with the relatively slow-burning smokeless gunpowders that are
classed as propellants.
DOUBLE-ACTION: A handgun mechanism where pulling the trigger
retracts and releases the hammer or firing pin to initiate
DUM-DUM BULLET: A British military bullet developed in Indiažs Dum-
Dum Arsenal and used on India's North West Frontier and in the
Sudan in 1897 and 1898. It was a jacketed .303 cal. British bullet
with the jacket nose left open to expose the lead core in the hope
of increasing effectiveness. Improvement was not pursued, for the
Hague Convention of 1899 (not the Geneva Convention of 1925, which
dealt largely with gas warfare) outlawed such bullets for warfare.
Often "dum-dum" is misused as a term for any soft-nosed or hollow-
pointed hunting bullet.
EXPANDING BULLET: One designed to increase in diameter on entering
a target. Almost all rifle bullets intended for hunting are
intended to expand on impact.
EXPLODING BULLET: A projectile containing an explosive component
that acts on contact with the target. Seldom found and generally
ineffective as such bullets lack the penetration necessary for
defense or hunting.
EXPLOSIVE: Any substance (TNT, etc.) that, through chemical
reaction, detonates or violently changes to gas with accompanying
heat and pressure. Smokeless powder, by comparison, deflagrates
(burns relatively slowly) and depends on its confinement in a gunžs
cartridge case and chamber for its potential as a propellant to be
FIREARM: A rifle, shotgun or handgun using gunpowder as a
propellant. By federal definition, under the 1968 Gun Control Act,
antiques are excepted. Under the National Firearms Act, the word
designates machine guns, etc. Airguns are not firearms.
FIXED AMMUNITION: A complete cartridge of several obsolete types
and of today's rimfire and center-fire versions.
FLASH HIDER/FLASH SUPPRESSOR: A muzzle attachment intended to
reduce visible muzzle flash caused by the burning propellant.
GAUGE: The bore size of a shotgun determined by the number of round
lead balls of bore diameter that equals a pound.
GUN: The British restrict the term in portable arms to shotguns.
Here it is properly used for rifles, shotguns, handguns and
airguns, as well as cannon.
GUNPOWDER: Chemical substances of various compositions, particle
sizes, shapes and colors that, on ignition, serve as a propellant.
Ignited smokeless powder emits minimal quantities of smoke from a
gun's muzzle; the older blackpowder emits relatively large
quantities of whitish smoke.
HANDGUN: Synonym for pistol.
HIGH-CAPACITY MAGAZINE: An inexact, non-technical term indicating
a magazine holding more rounds than might be considered "average."
HOLLOW-POINT BULLET: A bullet with a concavity in its nose to
increase expansion on penetration of a solid target.
JACKET: The envelope enclosing the core of a bullet.
LEVER-ACTION: A gun mechanism activated by manual operation of a
MACHINE GUN: A firearm of military significance, often crew-served,
that on trigger depression automatically feeds and fires cartridges
of rifle size or greater. Civilian ownership in the U.S. has been
heavily curtailed and federally regulated since 1934.
MAGAZINE: A spring-loaded container for cartridges that may be an
integral part of the gunžs mechanism or may be detachable.
Detachable magazines for the same gun may be offered by the gunžs
manufacturer or other manufacturers with various capacities. A gun
with a five-shot detachable magazine, for instance, may be fitted
with a magazine holding 10, 20, or 50 or more rounds. Box magazines
are most commonly located under the receiver with the cartridges
stacked vertically. Tube or tubular magazines run through the stock
or under the barrel with the cartridges lying horizontally. Drum
magazines hold their cartridges in a circular mode. A magazine can
also mean a secure storage place for ammunition or explosives.
MAGNUM: A term indicating a relatively heavily loaded metallic
cartridge or shotshell and, by extension, a gun safely constructed
to fire it.
MULTI-BARRELED: A gun with more than one barrel, the most common
being the double-barreled shotgun.
MUSHROOMED BULLET: A description of a bullet whose forward diameter
has expanded after penetration.
MUZZLE: The open end of the barrel from which the projectile exits.
MUZZLE BRAKE: An attachment to or integral part of the barrel
intended to trap and divert expanding gasses and reduce recoil.
MUZZLELOADER: The earliest type of gun, now also popular as modern-
made replicas, in which blackpowder and projectile(s) are
separately loaded in through the muzzle. The term is often applied
to cap-and-ball revolvers where the loading is done not actually
through the muzzle but through the open ends of the cylinderžs
PELLETS: Small spherical projectiles loaded in shotshells and more
often called "shot." Also the skirted projectiles used in pellet
PELLET GUN: A rifle or pistol using compressed air or CO2 to propel
a skirted pellet as opposed to a spherical BB. Not a firearm.
PISTOL: Synonymous with "handgun." A gun that is generally held in
one hand. It may be of the single-shot, multi-barrel, repeating or
semi-automatic variety and includes revolvers.
PISTOL GRIP: The handle of a handgun or protrusion on the buttstock
or fore-end of a shoulder-operated gun that resembles the grip or
handle of a handgun. A "semi-pistol grip" is one less pronounced
than normal; a "vertical pistol grip" is more pronounced than
PLINKING: Informal shooting at any of a variety of inanimate
targets. The most often practiced shooting sport in this country.
PRIMER: The ignition component of a cartridge, generally made up of
a metallic fulminate or (currently) lead styphnate.
PROPELLANT: In a firearm the chemical composition that is ignited
by the primer to generate gas. In air or pellet guns, compressed
air or CO2.
PYRODEX: A trade name for a blackpowder substitute, the only such
safe substitute known at this time.
RECEIVER: The housing for a firearm's breech (portion of the barrel
with chamber into which a cartridge or projectile is loaded) and
REVOLVER: A gun, usually a handgun, with a multi-chambered cylinder
that rotates to successively align each chamber with a single
barrel and firing pin.
RIFLE: A shoulder gun with rifled bore.
RIFLING: Spiral grooves in a gun's bore that spin the projectile in
flight and impart accuracy. Rifling is present in all true rifles,
in most handguns and in some shotgun barrels designed for
increasing the accuracy potential of slugs( a slug is a single
projectile rather than the more common "shot".)
RIMFIRE: A rimmed or flanged cartridge with the priming mixture
located inside the rim of the case. The most famous example is the
.22 rimfire. It has been estimated that between 3-4 billion .22
cartridges are loaded in the U.S. each year.
ROUND: Synonym for a cartridge.
SABOT: A lightweight carrier surrounding a heavier projectile of
reduced caliber, allowing a firearm to shoot ammunition for which
it is not chambered. For example, a hunter could use his .30-30
deer rifle to shoot small game with .22 centerfire bullets.
SATURDAY NIGHT SPECIAL: A catchy phrase having no legal or
SAWED-OFF SHOTGUN (RIFLE): Common term for federally restricted
"short-barreled shotgun (rifle)" i.e. a conventional shotgun with
barrel less than 18" (rifle less than 16") or overall length less
SELECTIVE-FIRE: A firearm's ability to be fired fully
automatically, semi-automatically or, in some cases, in burst-fire
mode at the option of the firer.
SEMI-AUTOMATIC: A firearm designed to fire a single cartridge,
eject the empty case and reload the chamber each time the trigger
SHOTGUN: A shoulder gun with smooth-bored barrel(s) primarily
intended for firing multiple small, round projectiles, (shot,
birdshot, pellets), larger shot (buck shot), single round balls
(pumpkin balls) and cylindrical slugs. Some shotgun barrels have
rifling to give better accuracy with slugs or greater pattern
spread to birdshot.
SHOTSHELL: The cartridge for a shotgun. It is also called a
"shell," and its body may be of metal or plastic or of plastic or
paper with a metal head. Small shotshells are also made for rifles
and handguns and are often used for vermin control.
SILENCER: A virtually prohibited device for attachment to a gun's
muzzle for reducing (not silencing) the report. Better terms would
be "sound suppressor" or "sound moderator."
SINGLE-SHOT: A gun mechanism lacking a magazine where separately
carried ammunition must be manually placed in the gun's chamber for
SLIDE-ACTION: A gun mechanism activated by manual operation of a
horizontally sliding handle almost always located under the barrel.
"Pump-action" and "trombone" are synonyms for "slide-action."
SNUB-NOSED: Descriptive of (usually) a revolver with an unusually
SUBMACHINE GUN: An automatic firearm commonly firing pistol
ammunition intended for close-range combat.
TEFLON: Trade name for a synthetic sometimes used to coat hard
bullets to protect the rifling. Other synthetics, nylon for
instance, have also been used as bullet coatings. None of these
soft coatings has any effect on lethality.
WEAPON: Webster defines it as "an instrument of offensive or
defensive combat." Thus an automobile, baseball bat, bottle, chair,
firearm, fist, pen knife or shovel is a "weapon," if so used.
This information is provided as a service of the National Rifle
Association Institute for Legislative Action, Fairfax, VA.
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