ShKAS machine gun The ShKAS ( Shpitalny - Komaritski Aviatsionny Skorostrelny , Shpitalny - Komaritski rapid fire machine gun for aircraft ; Russian : ШКАС - Шпитальный - Комарицкий Авиационный Скорострельный ) is a 7 . 62 mm machine gun widely used by Soviet aircraft in the 1930s and during World War II . It was designed by Boris Shpitalniy and Irinarkh Komaritsky and entered production in 1934 . ShKAS was used in the majority of Soviet fighters and bomber s and served as the basis for the ShVAK cannon . Description . ShKAS is a gas - operated revolver - type machine gun ; it has however a single chamber in which the pin strikes the primer . A key element of the ShKAS ' high rate of fire is the revolving drum ( feed cage ) that holds ten rounds and provides a very smooth , progressive removal of the cartridges from their disintegrating link belt . Another element is the lightweight recoiling portion of the gun , weighing only 921 grams ( 2 . 07 lb ) . A declassified US analysis of the feed system , based on models captured during the Korean War , reads : After analyzing the less unusual parts of the ShKAS , the US source concludes : Although ShKAS is best known for its high rate of fire , it did have provisioning for slower cyclic rates . This was done by " changing the position of the holes in the gas regulator , which comes with holes of three different sizes , 1 / 12 - inch , 1 / 10 - inch and 1 / 8 - inch . The smaller the orifice used , the more moderate is the rate of fire obtained . " Variants . Initial production consisted of cable - charged wing - mounted and turret - mounted ShKAS with a synchronized version entering service in 1936 . By 1952 Western intelligence had identified five different models , all including the number " 426 " in their markings : " KM " stands for " constructed model " , i . e . production . The intended role was marked with the letters " T " for flexible , " K " for wing , and " S " synchronized . The flexible version was usually mounted in a Soviet copy of the Scarff ring . The 1937 model had slightly higher maximum rate of fire of 2 , 000 rounds per minute . The amount of ammunition normally carried was 750 rounds for the fixed models and 1 , 000 to 1 , 500 for the flexible . Soviet archives indicate the following production volumes , by year : In 1939 , a small number of Ultra - ShKAS were produced featuring a firing rate of 3 , 000 rounds per minute but these saw only limited use due to reliability problems . Effectiveness . A one - second burst from four ShKAS in Polikarpov I - 153 or Polikarpov I - 16 placed 120 bullets within 15 angular mil s at 400 meters ( 1 , 312 feet ) giving a firing density of 5 bullets per square meter of the sky . This was significantly higher than contemporary aircraft from other nations , especially considering that four guns with 650 rounds of ammunition per gun weighed a total of only 160 kg ( 350 lb ) . But ShKAS had its defects . Soviet machine - gun technician Viktor M . Sinaisky recalled : 7 . 62 mm ammunition specifications . Although chambered in the 7 . 62x54R , the ShKAS guns used cartridges specially built for them to smaller tolerances ; to distinguish them from the regular 7 . 62 ammunition , the letter " Sh " ( Ш ) was imprinted on the bottom of the cases . The cases , designed by N . M . Elizarov , also had a few additional features like double crimping and a thicker case wall of " bimetallic " construction instead of the traditional brass . The main type of bullet used was armor - piercing incendiary B - 32 bullet . Possible influences . Some military historians consider that feed system of the Mauser MG 213 C ( the seminal revolver cannon for Western designs ) was inspired by the ShKAS .