After studying the excellent British Bofors model anti-aircraft gun in the early 1930s, Soviet designers determined that a larger caliber gun was needed. Thus the 37mm M1939 61-K was developed, entering service in 1940 and seeing action throughout World War II. Nearly 15,000 low- and medium-altitude aircraft would ultimately be shot down by these superb AA guns, which would remain in service until the 1950s.

The 61-K could fire up to 60 rounds per minute at a muzzle velocity of 880 meters per second. It could hit aircraft at altitudes up to 6700 meters. This gun also proved effective as a direct fire field piece for use against enemy light armor, as it could penetrate 37mm of armor at a range of 500 meters. More than 20,000 of these guns were ultimately built, with both land-based and ship-based naval versions seeing action.

For transportation, the gun was mounted on a four-wheeled carriage that could be towed by truck or other vehicle. When deployed for firing, the carriage was supported by four screw jacks for firing stability.