The Type 97 heavy tank machine gun (九七式車載重機関銃 Kyū-nana-shiki shasai jū-kikanjū?) was the standard machine gun used in tanks and armored vehicles of the Imperial Japanese Army during World War II, This weapon was not related to the Type 97 aircraft machine gun used in several Japanese Navy aircraft including the A6M Zero. It was also heavy for a magazine fed weapon and its calibre.
Initially, the Type 11 Light Machine Gun was modified by the Army Technical Bureau for use in tanks and other armored vehicles, and was produced for this application under the designation “Type 92 Mobile Machine Gun”. However, the basic design issues with the Type 11 remained, including its tendency to jam because of the slightest amount of grit or dirt, and the low lethality and lack of stopping power of its 6.5x50mm Arisaka cartridges. During the early stages of the Second Sino-Japanese War, Japanese forces captured a number of Czech ZB vz/26 light machine guns from China’s National Revolutionary Army; its numerous design advantages led to the development of the Type 97. This was used in a modified form for armored vehicles until 1940, when the Japanese Army switched to a rimless 7.7 mm cartridge.
The Type 97 was mechanically similar to the Czech ZB vz. 26, with a different stock and pistol grip. It had a straight, vertical, 20-round box magazine and used the same 7.7 mm cartridges used in the Type 99 rifle. The gun barrel could easily overheat, which meant the gunner had to fire in bursts, or the barrel would be shot out. When fitted in a tank, a fixed focus 1.5x telescopic sight with a 30° field of view was used. To prevent injury to the gunner, a rubber eye pad was attached to the rear of the sight. When used as an infantry weapon, a bipod was installed. Without the bipod, it weighed 11.25 kg (24.8 lb).