The ZiS-2 (Russian: ЗиС-2) was a Soviet 57-mm anti-tank gun used during World War II. The ZiS-4 was a version of the gun meant to be installed in tanks. ZiS stands for Zavod imeni Stalina (Russian Завод имени Сталина, "plant named after Stalin"), the official title of Artillery Factory No. 92, which produced the gun first.
It is a semi-automatic gun with vertical block breech. When firing the block opens and closes automatically, the loader only has to put a round into the receiver. Due to this feature the rate of fire can reach 25 rounds per minute. The split-trail carriage with a gunshield was shared with the ZiS-3 divisional gun. The carriage had coil spring suspension, which allowed towing with a speed of up to 50 km/h (31 mph) on highways, 30 km/h (19 mph) on unpaved roads and 10 km/h (6.2 mph) off-road. The gun can also be attached to a limber and towed by a team of six horses or on the Universal Carrier. ZiS-2s are equipped with PP1-2 panoramic sights.
Tank version of this gun, the ZiS-4, is used in T-34/57 tank.