A pneumatic gun discharged by the elastic force of air or carbon dioxide.  A gun from which a missile is discharged by compressed gas.  Missiles include 4.5 mm (.177) and 5.5 mm (.22) metal pellets, and 4.5 mm (.177) ball bearings.


Additional note: In Great Britain some airguns (an air rifle with a muzzle energy greater than 12 foot pounds (16.3 joules), an air pistol with a muzzle energy greater than 6 foot pounds or any air weapon which uses a self-contained gas cartridge system) require a firearms certificate.  It is an offence to carry an airgun in a public place without a reasonable excuse or, in the case of anyone under the age of 17, without adult supervision.




A sport or recreational pastime in which players participate in the simulation of military- or law enforcement-style combat using replicas of real firearms.




Usually a realistic firearm which is discharged by a spring/piston or compressed gas.  Fires spherical 6 mm plastic ball bearings (airsoft BBs) only (c.f. ball bearing guns), with a maximum projectile weight of 0.43 g.  Has a muzzle velocity below 300 ft/s with a  power of less than 1 joule.




Cartridges or shotgun shells, including the primers, loads (powder), casings, bullets, wads and shot.




A weapon that continues to fire as long as the trigger is held down and it still contains ammunition. A "machine gun."




A type of airgun designed to fire spherical projectiles (BBs), usually from a .177 (4.45 mm) smoothbore barrel. Modern BBs are steel, plated with zinc or copper (c.f. airsoft BBs).  Some manufacturers make lead BBs, which are generally intended for use in rifled barrels.  Fires at velocities capable of causing harm to people or animals. Many have been designed to look like real guns.




A handgun, such as a starting pistol, that has been heavily modified from a regular pistol to make it incapable of using real bullets.  Uses blank shells or caps to prevent injury.


Additional note: Blank-firing pistols have been modified illegally to fire live ammunition.




The hole through the centre of a gun barrel, through which the bullet travels. The bore may be smooth (shotguns and muskets) or rifled (rifles and handguns).

full bore - having an inside diameter of greater than 0.22 in.


small bore - having an inside diameter of 0.22 in or less.




The inside diameter of the gun's bore, measured in inches (e.g. .22, .357) or millimetres (e.g. 9 mm).




A short-barrelled and often lightweight rifle.  It is generally less powerful than a rifle of a given period.




A real weapon that has been engineered so that it is no longer capable of firing bullets.


Additional notes: In Great Britain deactivation must be carried out to an approved Home Office standard, more stringent since 1995 (standards were not retrospective).  No licences are required for these guns.




A weapon that fires either single or multiple projectiles at high velocity by the gases produced through rapid, confined burning of a propellant.  In older firearms this was black powder, but modern firearms use smokeless powder, cordite or other propellants.


The term gun is often used as a synonym, although in specialist use has a restricted sense,




The measure of the bore of a shotgun.  The larger the number, the smaller the bore. The gauge actually describes the number of lead balls the diameter of the bore that it would take to make a pound (e.g., a lead ball that would exactly fit the barrel of a 20-gauge shotgun would weigh 1/20 pound).




A firearm designed to be held in one hand.

pistol - originally referred to any handgun except a revolver, but that distinction is often lost today.  Semi-automatic pistols (usually between .22 and .45 calibre) fire one cartridge for each trigger pull.  Often designed to fire 10 or more bullets from a single magazine.

revolver - a handgun with a cylinder containing multiple chambers.  Each chamber is loaded by hand, and firing the revolver causes the cylinder to turn and line up the next chamber.

Additional note: Prohibited weapons in Great Britain.



An imitation gun is anything which has the appearance of being a firearm whether or not it is capable of discharging any shot, bullet or other missile.


Additional note: It is an offence to carry an imitation gun in a public place without legitimate reason in Great Britain




A deactivated weapon that has been engineered to fire bullets again.


Additional note: Reactivation is an offence in Great Britain.




A replica gun cannot fire ammunition but is manufactured to resemble a well known model of weapon, involving an impressive level of detail (see Imitation Gun).


Additional note: It is an offence to carry an imitation gun in a public place without legitimate reason in Great Britain




A shoulder-fired long gun with rifling (spiral grooves cut in the bore to make the bullet spin, which improves accuracy).


Additional note: Require a firearms certificate in Great Britain.




A gun that uses the recoil to eject the spent cartridge and load a fresh round into the chamber. There is no manually cocking or loading required between shots. The trigger must be pulled once per shot, unlike a fully automatic weapon, which will continue firing as long as the trigger is held.




A shoulder-fired long gun with no rifling in the barrel, designed to shoot a large number of small projectiles (shot) rather than a single large projectile (a bullet).


Additional note: Require a shotgun certificate in Great Britain.


1 From Wikipedia


2 From Firearm Terminology by Gary D Robson



Some additional information on British firearms legislation and punishments can be found in a recent BBC Article






Facts about Guns

How Britain Compares with Other Countries

Firearms and Suicide

Gun Deaths and Injuries in the UK