XM913 chain gun
The XM913 is an experimental American chain gun produced at Picatinny Arsenal. The cannon is a larger and more modern version of the 25 mm Bushmaster cannon. Although its shells, 50 x 228 mm, are twice the diameter of the 25mm M242 Bushmaster, the 50mm cannons is not much longer than the smaller weapon. The overall lengths of the 25mm cannon and 50mm cannon are and , respectively; while the portion of the gun that intrudes into the turret are and , respectively. Ammunition. The XM1204 High Explosive Air Burst round is programmable. The gunner  can select from three detonation modes. The XM1203 Armor Piercing Fin Stabilized Discarding Sabot with Trace. The projectile itself is 50 mm in diameter, encasing a long thin dart, designed to pierce armored vehicles. A light "sabot" grips the barrel's rifling, in order for the shell gets the full power of the expanding gas. Tracer rounds have a button of pyrotechnical chemical that leave a trail to help a gunner figure out their fall of shot.