The Gatling gun is one of the best known early rapid-fire weapons, invented by Richard Gatling, known for its use by the Union forces during the American Civil War. The Gatling gun's operation centered on a cyclic multi-barrel design which facilitated cooling and synchronized the firing/reloading sequence. Another multi-barrel design is the hydraulically-driven GAU-8 Avenger 30 mm cannon, carried on the A-10 Thunderbolt II (Warthog) attack aircraft.
A combat shotgun is a shotgun that is intended for use in an offensive role. The development of the repeating pump action shotguns in the 1890s led to their use by US Marines in the Philippines insurrections, but the modern concept of the combat shotgun was fully developed by the American Expeditionary Forces during World War I. The shotgun was used by Allied forces and Allied supported partisans in all theaters of combat in World War II.
The M2 Machine Gun or Browning .50 Caliber Machine Gun, is a heavy machine gun designed towards the end of World War I by John Browning. It is very similar in design to Browning's earlier M1919 Browning machine gun. It has been used extensively as a vehicle weapon and for aircraft armament by the United States from the 1920s to the present.