two rounds. Eventually, the M163 was replaced in US service by the M1097 Avenger and the M6 Linebacker, an M2 Bradley with FIM-92 Stinger missiles instead of the standard TOW anti-tank guided missiles: the Stinger missile providing the necessary range to deal with helicopters with anti-tank missiles far out-ranging the 20 mm gun, as well as considerably extending the reach against fixed-wing targets. The final US Army VADS-equipped unit at Fort Riley Kansas completed turn-in of its Vulcans in 1994. Ammunition While a large number of 20x102 mm round have been developed, not all were issued to M163 units. M246 HEI-T-SD was developed alongside the system and was the primary anti-air round, with M56 HEI being used for ground support. PIVADS units could use Mk 149 APDS rounds, which greatly increase maximum effective range due to their higher velocity and lack of a self-destruct. M940 may have been issued for use prior to withdrawal from service, though sources are unclear. Specifications Armour layout: front: sides: rear/top: bottom: M168 gun on the M163: Effective range: M246 (air targets): Mk149 (air targets): M56 (ground targets): Maximum firing range: M246: self-destruct Maximum rate of fire: 1,000 rpm unlimited, 3,000 rpm in burst of 10,30, 60, or 100 rounds Elevation: +80° to −5° at 45°/second Traverse: 360° at 60°/s Ammunition: M167: 500 rounds. M163: 1,100 rounds loaded, 1,000 rounds stowed Variants M163 M163A1 changes to gun mount and vehicle to bring it in line with the M113A1. The resulting carrier vehicle was designated M741A1. M163A2 powertrain changes to bring it in line with the M113A2. The resulting carrier vehicle was designated M741A2. M163 PIVADS (1984) accuracy and workload improvements developed by Lockheed Electronics Company including a digital microprocessor, director sight and low backlash azimuth drive system. The PIVADS used the M741A1 carrier vehicle, and the improvements were carried over to the M163A2. M167 towed version of the turret. Prime mover was the Gama Goat until 1989 when the Humvee replaced it. Machbet Israeli upgraded version equipped with 4-tube FIM-92 Stinger pod, upgraded tracking system and the ability to share information with local high-power radar. History of service In the Israeli Air Defense Command the "Hovet" (the Israeli designation to the M163 VADS) scored 3 shoot-downs, including the first shoot-down of a jet warplane (a Syrian MiG-21 fighter jet) by the M163 VADS, during Operation Peace for Galilee in 1982. The Israel Defense Forces used