The MK44 cannon is an advanced derivative of the combat proven M242 Bushmaster cannon intended for ground fighting forces. It has been selected for the USMC AAAV/EFV next generation amphibious assault vehicle, now called the EFV, and the US Air Force plans to provide a modified Mk 44 variant to the AC-130U gunship.

The Mk 44 40-caliber cannon fires 30mm ammunition. The US Air Force Special Operations Command awarded ATK a $8.8 million development contract November 1, 2004, covering the Mk 44 modifications to fit into the AC-130U aircraft. The Mk 44 will be installed as a side-firing cannon to perform surgical attacks against ground targets by AC-130Us.

On 15 September 2005, the UK Royal Navy ordered the 30/40mm Mk 44 Bushmaster cannon to equip its Type 23 frigates with the aim to counter fast attack craft (FAC) and fast inshore attack craft (FIAC) threats. MSI Defence Systems will take care of integrating the Mk 44 cannon onto its DS30M Mk2 Naval Mounting. This naval mounting also includes laser range finder, a thermal imager, an electro-optical director and a color TV camera. Deliveries of the 26 cannons on order were expected to begin in late 2006. The contract was valued at £15 million over a 8-year period.