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
Not a firearm but a gun that uses compressed air or CO2 to
propel a projectile. Examples: BB gun, pellet gun, CO2 gun.
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 rifles,
multiple pellets or single slugs in shotguns). Sometimes
called "fixed ammunition" to differentiate from components
inserted separately in muzzleloaders.
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.
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."
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.
Any weapon used in an assault (see WEAPON).
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.
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 novice.
Originally a spherical projectile, now generally a fully
jacketed bullet of cylindrical profile with round or pointed
nose. Most commonly used in military terminology.
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 pressure levels.
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
A gun mechanism activated by manual operation of the
breechblock that resembles a common door bolt.
The interior of a firearm's barrel excluding the chamber.
A synonym for expended metallic cartridge cases.
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,
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
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.
A single, complete round of ammunition.
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."
A cartridge with its primer located in the center of the
base of the case.
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.
A constriction at or near the muzzle of a shotgun barrel
that affects shot dispersion.
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.
An inflammatory phrase having neither historical basis nor
legal or technical meanings.
The drum of a revolver that contains the chambers for the
A small single-shot or multi-barreled (rarely more than two)
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.
A handgun mechanism where pulling the trigger retracts and
releases the hammer or firing pin to initiate discharge.
A British military bullet developed in India's 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
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.
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 gun's cartridge case and chamber for its potential as a
propellant to be realized.
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.
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.
The bore size of a shotgun determined by the number of round
lead balls of bore diameter that equals a pound.
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.
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.
Synonym for pistol.
An inexact, non-technical term indicating a magazine holding
more rounds than might be considered "average."
A bullet with a concavity in its nose to increase expansion
on penetration of a solid target.
The envelope enclosing the core of a bullet.
A gun mechanism activated by manual operation of a lever.
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
A spring-loaded container for cartridges that may be an
integral part of the gun's mechanism or may be detachable.
Detachable magazines for the same gun may be offered by the
gun's 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
A term indicating a relatively heavily loaded metallic
cartridge or shotshell and, by extension, a gun safely
constructed to fire it.
A gun with more than one barrel, the most common being the
A description of a bullet whose forward diameter has
expanded after penetration.
The open end of the barrel from which the projectile exits.
An attachment to or integral part of the barrel intended to
trap and divert expanding gasses and reduce recoil.
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 cylinder's chambers.
A rifle or pistol using compressed air or CO2 to propel a
skirted pellet as opposed to a spherical BB. Not a firearm.
Small spherical projectiles loaded in shotshells and more
often called "shot." Also the skirted projectiles used in
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.
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 normal.
Informal shooting at any of a variety of inanimate targets.
The most often practiced shooting sport in this country.
The ignition component of a cartridge, generally made up of
a metallic fulminate or (currently) lead styphnate.
In a firearm the chemical composition that is ignited by the
primer to generate gas. In air or pellet guns, compressed
air or CO2.
A trade name for a blackpowder substitute, the only such
safe substitute known at this time.
The housing for a firearm's breech (portion of the barrel
with chamber into which a cartridge or projectile is loaded)
and firing mechanism.
A gun, usually a handgun, with a multi-chambered cylinder
that rotates to successively align each chamber with a
single barrel and firing pin.
A shoulder gun with rifled bore.
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
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.
Synonym for a cartridge.
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
SATURDAY NIGHT SPECIAL
A catchy phrase having no legal or technical meaning.
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 than 26."
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.
A firearm designed to fire a single cartridge, eject the
empty case and reload the chamber each time the trigger is
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.
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.
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."
A gun mechanism lacking a magazine where separately carried
ammunition must be manually placed in the gun's chamber for
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
Descriptive of (usually) a revolver with an unusually short
An automatic firearm commonly firing pistol ammunition
intended for close-range combat.
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.
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