The Browning Automatic Rifle (BAR) is a family of American automatic rifles and machine guns used by the United States and numerous other countries during the 20th century. 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 American Expeditionary Forces in Europe as a replacement for the French-made Chauchat and M1909 Benét–Mercié machine guns that US forces had previously been issued.

An automatic rifle is a type of autoloading rifle that is capable of fully automatic fire. Automatic rifles are generally select-fire weapons capable of firing in semi-automatic and automatic firing modes. Automatic rifles are distinguished from semi-automatic rifles in their ability to fire more than one shot in succession once the trigger is pulled. Most automatic rifles are further subcategorized as battle rifles or assault rifles.