M1918 Browning Automatic Rifle
The Browning Automatic Rifle (BAR) is a family of United States automatic rifles (or machine rifles) and light machine guns used by the United States and numerous other countries during the 20th century. This machine rifle is similar in function to other related World War I automatic rifles used for assaulting the enemy. See also: Firearms Semantics: “Battle Rifle” and “Assault Rifle”. Other light machine guns used by troops advancing across no-man's-land were the Chauchat, Benet-Mercie and the Lewis gun.
The primary variant of the BAR series was the M1918, chambered for the .30-06 Springfield rifle cartridge and designed by John Browning in 1917 for the U.S. Expeditionary Corps in Europe as a replacement for the French-made Chauchat and M1909 Benét–Mercié machine guns the Doughboys had previously been issued.
The BAR was designed to be carried by infantrymen during an assault or advance while supported by the sling over the shoulder or fired from the hip. This is a concept called "walking fire" — thought to be necessary for the individual soldier during trench warfare. The BAR never entirely lived up to the original hopes of the War Department; being neither a rifle nor a machine gun.