which recognized the incendiary rounds as grenades, thus it was called autocannon. The AN/M2 was also produced in Finland under the export name Colt MG 53-2. M296 The XM296/M296 is a further development of the AN/M2 machine gun for the OH-58 Kiowa Warrior helicopter. The M296 differs from previous remote firing variants in that it has an adjustable firing rate (500–850 rpm), while lacking a bolt latch (allowing single-shot operation). As an air-cooled gun used aboard a relatively slow rotary-wing aircraft, the M296 has a burst restriction rate of 50 rounds per minute sustained fire or 150 rounds per minute maximum while conducting peacetime training requirements; the combat firing rate is unrestricted but a ten-minute cooling period after prolonged firing is mandated to avoid stoppages due to overheating. XM213/M213, XM218, GAU-15/A, GAU-16/A, and GAU-18/A The XM213/M213 was a modernization and adaptation of existing .50 caliber AN/M2s in inventory for use as a pintle-mounted door gun on helicopters using the M59 armament subsystem. The GAU-15/A, formerly identified as the XM218, is a lightweight member of the M2/M3 family. The GAU-16/A was an improved GAU-15/A with modified grip and sight assemblies for similar applications. Both of these weapons were used as a part of the A/A49E-11 armament subsystem (also known as the Defensive Armament System). The GAU-18/A is a lightweight variant of the M2/M3 and is used on the USAF's MH-53 Pave Low and HH-60 Pave Hawk helicopters. These weapons use the M2HB barrel and are typically set up as left-hand feed, right-hand charging weapons, but on the HH-60 Pave Hawks that use the EGMS (External Gun Mount System) the gun is isolated from the shooter by a recoil-absorbing cradle and all weapons are set up as right-hand charge but vary between left- and right-hand feed depending on what side of the aircraft it is on. A feed chute adapter is attached to the left- or right-hand feed pawl bracket allowing the weapon to receive ammunition through a feed chute system connected to externally mounted ammunition containers holding 600 rounds each. AN/M3, GAU-21/A, and M3P During World War II, a faster-firing Browning was developed for aircraft use. The AN/M3 increased the rate of fire to around 1,200 rounds per minute while firing the same round with minimal change in weight or size. The AN/M3 was used in Korea on the P-51D-30, F-82 Twin Mustang (the XP-82 mounted a total of 14 AN/M3