m1918 bar
The M1918 Browning Automatic Rifle (BAR) is an American select-fire rifle chambered for .30-06 Springfield cartridge and designed by John Browning in 1917 for the American Expeditionary Forces in Europe as a replacement for the Chauchat. Though it is technically not a light machine gun, the BAR was frequently issued and used in that role, and as such is recognized as one today. The weapon is recognizable by its straight 20-round magazine, rectangular one-piece forearm, and a flip-up rear sight with a windage knob.
This tag also applies to any foreign-produced variants, such as the Polish Browning wz. 28 which notably has a pistol grip (Danbooru post #6539181) or the French MAS mle 1922.
In anime the BAR is best known for its usage by Charlotte E. Yeager from Strike Witches.