37 mm automatic air defense gun M1939 ( 61 - K ) 37 mm automatic air defense gun M1939 ( 61 - K ) ( " ' ) was a Soviet 37 mm caliber anti - aircraft gun developed during the late 1930s and used during World War II . The land based version was replaced in Soviet service by the ZSU - 57 - 2 during the 1950s . Guns of this type were successfully used throughout the Eastern Front against dive bombers and other low - and medium - altitude targets . It also had some usefulness against lightly armored ground targets . Crews of the 37 mm AD guns shot down 14 , 657 Axis planes . The mean quantity of 37 mm ammunition to shoot down one enemy plane was 905 rounds . Development . The Soviet Navy purchased a number of Bofors 25 mm Model 1933 guns in 1935 , trials of the weapon were successful and it was decided to develop a 45 mm version of the weapon designated the 49 - K . The development under the guidance of leading Soviet designers M . N . Loginov , I . A . Lyamin and L . V . Lyuliev was successful , but the army thought that the 45 mm calibre was a little too large for an automatic field weapon . In January 1938 the Artillery Factory Number 8 in Sverdlovsk was ordered to develop a 37 mm weapon based on the same design . The task was fulfilled by the chief designer of the Factory Mikhail Loginov and his assistant Lev Loktev . Firing trials of the new 61 - K were conducted in October 1938 . Competitive firing trials were conducted in 1940 between the 61 - K and the Bofors 40 mm / 56 . They found that there were no substantial differences between them . Land version . The weapon was initially installed as a single barrel weapon on a four wheeled ZU - 7 carriage , and was soon ready for service . An initial order for 900 units was placed . The gun was operated by a crew of eight men . A total of 200 rounds of ammunition were carried which were fed into the gun in five round clips . Total Soviet production was around 20 , 000 units , ending in 1945 . However , it has also been produced in Poland , China and North Korea . Armour penetration of the armour - piercing ( AP ) rounds is reported as 37 millimetres of Rolled homogeneous armour ( RHA ) at 60°at 500 metres range and 28 millimetres of RHA at 90° at 1500 meters range . Naval version . The naval mounting was produced as the 70K , and had entered service before the German invasion of the Soviet Union replacing the semi - automatic 45 mm / 46 21 - K on many ships . It was fitted in large numbers to Soviet ships during the Second World War , notably the T301 class minesweeper . The V70K was produced until 1955 , with a total of 3 , 113 built . One drawback was that the 70K required a barrel change after every 100 rounds fired . To improve on this , a twin barrelled water cooled mount , the V - 11 ( called " W - 11 " in East Germany and Poland because of different Cyrillic trasliteration ) , entered service in 1946 , and was in production until 1957 . A total of 1 , 872 V - 11 mounts were built . After this an 85 - caliber anti - aircraft mounts long version , the 45 mm / 85 , was developed and accepted into service in 1954 , it was deployed in twin and quad turrets on a number of classes of vessels , including the " Neustrashimy " , " Kildin " and " Kotlin " class destroyer s . However it was later replaced with the ZIF - 31 twin 57 mm mounting . The 37 mm twin mounting was exported to China where it was manufactured and used extensively , as the " Type 65 " . A turret based version was produced from the late 1980s called the " Type 76 " or H / PJA 76 . ZSU - 37 . The ZSU - 37 was developed late in the Second World War , it was a single 37 mm gun mounted in a large open turret on the chassis of the SU - 76 self - propelled gun . Ammunition . The cannon fires 37×252SR shells . The shells use brass cases lined with waxed paper and use KV - 2U percussion primers . A small piece of lead - tin wire is included in the case to act as a de - coppering agent , to counteract the buildup of copper from the driving bands of the projectiles . The Ammunition is produced in a number of countries including China , Russia , Egypt , Pakistan and Yugoslavia . The projectiles themselves are identical to those fired by the NS - 37 aircraft cannon . The explosive shells are fitted with point detonating fuzes making them unsuitable for engaging fast moving or small targets . Users . < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br > < br >