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 (Armor-Piercing Incendiary), HEI (High-Explosive Incendiary) and APFSDS-T (Armor-Piercing Fin-Stabilized Discarding Sabot-Tracer) variants. The gun can be converted to a caliber of 40x180 mm, which involves changing the barrel and a few key parts, to use the SuperShot 40 cartridge. It can also be converted to use the 30x170 mm RARDEN cartridge. History The Bushmaster II is the standard primary armament of the Bionix-II AFV currently in service with the Singapore Army, the KTO Rosomak in Polish service, and the CV90 AFVs in Finnish, Norwegian and Swiss service. Although the United States Air Force selected this cannon to replace the 25 mm GAU-12 Equalizer and Bofors 40 mm Automatic Gun L/60 guns on its fleet of AC-130U gunships in 2007. This plan was later canceled. The United States Marine Corps' Expeditionary Fighting Vehicle, which has been canceled, was expected to be armed with this cannon as well. Some United States Navy vessels, such as the new amphibious transport dock are armed with the Bushmaster II for surface threat defense. The Bushmaster II cannon is used in the DS30M Mark 2 Automated Small Calibre Gun (ASCG) point defense system that is fitted to the Royal Navy's Type 23 frigates. The Bushmaster II cannon is also used in the Turkish made Aselsan SMASH stabilized weapon station. The USAF had experimented with installing Bushmaster II cannons on their AC-130U gunships in place of the GAU-12 and Bofors 40 mm cannons. On 11 August 2008, the effort was canceled because of problems with the Bushmaster's accuracy in tests "at the altitude we were employing it." There were also schedule considerations that drove the decision. On 9 July 2012, the Air Force type classified a new version of the Bushmaster called the GAU-23/A. The cannon will be used on the AC-130W and the AC-130J gunships. The U.S. Navy uses the Mk44 Bushmaster II in the Mk 46 Mod 2 Gun Weapon System (GWS). The GWS is produced by General Dynamics to give warships protection against small, high-speed