A fully automatic rapid-firing rifle, which continues to fire bullets repeatedly as long as the trigger is depressed; lighter versions may be carried in the hands, and heavier versions may be mounted on a tripod, vehicle, or other mount. The lighweight versions are sometimes called a submachine gun.
(Maschinengewehr). Generally, an automatic weapon with ammunition fed from a belt, mounted on a tripod for firing from a fixed position. Early machine guns had water-cooled barrels, but essentially all now are air-cooled. 'Heavy' machine guns were water-cooled; 'light' ones were air-cooled. Some air-cooled machine guns are mounted on bipods for better mobility (less weight). The term is also often used generically for other automatic weapons. An 'automatic rifle' (automatische Gewehr) is generally a rifle designed to fire automatically from a 'box magazine' holding perhaps 20 cartridges. It usually can be fired from a bipod or from the shoulder or waist, and generally uses 'full- power' cartridges (a distinction from an 'assault rifle'). The best US example is the Model 1918 Browning Automatic Rifle (BAR). A submachine gun (British: machine pistol; German: Maschinenpistole) fires pistol cartridges, usually with blow-back action, and is designed to be highly portable. Use dictionaries and glossaries with particularly great care on this subject
1. A fully automatic firearm that loads, fires and ejects continuously when the trigger is held to the rear until the ammunition is exhausted or pressure on the trigger is released. 2. To Machine Gun: See Full Automatic, Runaway. Also known as Firing Full-Automatic.