Page "Firearm" Paragraph 3

Although the modern term " gun " is often used as a synonym for firearm, in specialist or military use it has a restricted sense referring only to an artillery piece with a relatively high muzzle velocity, such as a field gun, a tank gun, or a gun used in the delivery of naval gunfire ; or in sporting use for a shotgun.

Machine guns fire small-caliber ammunition ( generally (. 50 Cal ) or smaller ), and many machine guns are crew-served infantry support weapons, requiring the services of more than one crewman, just like artillery guns.

Hand-held firearms such as rifles, carbines, pistols and other small firearms, are rarely called " guns " in the restricted sense among specialists.

Artillery guns are much larger than these firearms, mounted on movable carriages, having bores of up to and weighing up to many tons.

Generally, an automatic firearm designed for a single user is referred to as an automatic rifle.

Other terms, including " firearm " itself, have been defined in specialized ad hoc ways by various legislation ; air weapons, for example, are sometimes so classified.