Also known as the "Ma Deuce", the M2 Heavy Barrel machine gun entered service with the U.S. Army in 1932 as an improvement to the original air-cooled, .50 caliber M2 invented by John Moses Browning and adopted by the Army as the Model 1921. In addition to the heavier, thicker barrel for better cooling, the M2HB also featured a means of quickly changing the barrel. Both the M2 and M2HB were used as anti-aircraft and anti-vehicle weapons, having originally begun development as an answer to the World War I German 13mm anti-tank rifle.
The M2HB wound up being used on just about everything with wheels, tracks or wings in the Army inventory (to say nothing of the Air Force, Coast Guard, Marines and Navy) , although its weight (84 pounds for the gun alone and another 44 for the tripod) meant that it was usually replaced by the lighter .30 caliber M1919 machine gun or the Browning Automatic Rifle as an infantry support weapon. As the ammunition feed could be set up to feed from either the right or left hand side of the weapon, dual and even quadruple mounts were not uncommon. The M2 is a popular weapon among NATO members as well as other nations who get most of their military hardware from the United States. Despite its age, the excellent design of the M2HB ensures that it continues to serve as an important weapon in arsenals around the world.