Automatic weapon capable of rapid, sustained fire, usually 5001,000 rounds per minute.
Developed in the late 19th century by such inventors as Hiram Maxim , it profoundly altered modern warfare. The World War I battlefield was dominated by the belt-fed machine gun, which remained little changed into World War II. Modern machine guns are classified into three groups: the squad automatic weapon, chambered for small-calibre assault-rifle ammunition and operated by one soldier; the general-purpose machine gun, firing full-power rifle ammunition and operated by two; and the heavy machine gun, firing rounds of 12.7 mm (.5 in) or higher and often mounted on an armoured vehicle. See also submachine gun .