surface craft. A Mk 46 turret consists of the 30 mm chain gun, a forward looking infrared (FLIR) sensor, a low light television camera, and a laser rangefinder. The guns fire at 200 rounds per minute and are fed by a 400-round magazine through 200-round dual feeds. Effective range is for full-caliber high-explosive or armor-piercing ammunition, which can be extended when using sub-caliber rounds. The Mk 46 GWS is permanently installed on the San Antonio-class amphibious transport dock and can be installed on and s as part of the surface warfare (SuW) package. In 2012, the Navy decided to replace the Mk 110 57 mm cannons on s with the Mk 46 GWS. Orbital ATK developed a modified version of the Bushmaster II, known as the Mk44 STRETCH, which can fire the 30x173mm Mk310 PABM-T airburst round. In January 2020, Northrop Grumman revealed the development of proximity airburst rounds for the LCS' 30 mm gun modules to destroy small unmanned aerial vehicles (UAVs). Since the modules feature dual feeders, different types of rounds could be fed for different targets. XM813 The XM813 Bushmaster is based on the Mk44 and is offered as an upgrade for U.S. Army M1126 Stryker and M2 Bradley vehicles, as well as having been a contender to be the primary armament of the Ground Combat Vehicle. Improvements include a 2.54 cm (1 inch) longer barrel, integral mount to increase first round hit probability by up to 10%, a dual recoil system to enhance accuracy and cope with future hotter propellants, and a Meggitt linkless dual feed ammunition system. The 30 mm chain gun can fire Mk310 Programmable Air Burst Munition rounds to attack targets in defilade. The United States Army Research, Development and Engineering Command helped enhance the XM813 mainly for safety and turret integration. By changing five parts, the gun caliber can be increased to 40 mm. As of November 2013, the XM813 was being tested at Aberdeen Proving Ground over three months to ensure reliability levels of 40,000 mean rounds between failures. Long-term plans are to equip vehicles with the Bushmaster III 35mm/50mm cannon. The XM813 was demonstrated in September 2014 at the ARDEC Digital Multi-Purpose Range Complex. The gun was mounted on a Bradley Fighting Vehicle and fired at targets up to away. An enhanced fire control system improves long-range accuracy to kill targets with fewer bursts, sometimes as few as two or