The Mk44 Bushmaster II is a 30 mm chain gun manufactured by Northrop Grumman. It is a derivative of the 25 mm M242 Bushmaster, and uses 70% of the same parts as the M242 while increasing the firepower by as much as 50% with the 20% increase in caliber size. The barrel is chromium-plated for extended life. The gun uses standard GAU-8 Avenger ammunition that is available in API, HEI and APFSDS-T variants.

The 30 mm caliber is a range of autocannon ammunition. It includes the NATO standardized Swiss 30×173mm, the Soviet 30×155mmB, 30×165mm and 30×210mmB, the Czechoslovak 30×210mm, the Yugoslav 30×192mm, the British 30×113mmB, and the French 30×150mmB and 30×170mm cartridges.