37mm Type-55 (M-1939)/Type-65

The 37 mm automatic air defense gun M1939 (61-K) (Russian: 37-мм автоматическая зенитная пушка образца 1939 года (61-К)) is a Soviet 37 mm calibre 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 AZP S-60 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 armoured ground targets.