Type 97 automatic cannon

The Type 97 automatic cannon is a Japanese anti-tank rifle that began development in the 1930s. It was used by the Imperial Japanese Army (IJA) during the Second Sino-Japanese War, the Soviet–Japanese border conflicts and the Pacific War. Ever-greater thicknesses of armour on tanks rendered the Type 97 obsolete by about 1942. This weapon was not related to the Type 97 heavy tank machine gun used in armored vehicles or the Type 97 aircraft machine gun used in Japanese Navy aircraft. Concerned by reports of Chinese purchases of Vickers six-ton tanks and rising tensions with the Soviet Red Army along the Manchurian border, the IJA issued a requirement for an anti-tank rifle in 1935. The Nagoya Arsenal submitted a weapon derived from their copy of the Hotchkiss M1929 machine gun while the Kokura Arsenal submitted a new design using a 20×125 mm cartridge. The first round of testing in March 1936 was not satisfactory and both guns were returned to their designers to rectify problems encountered during the trials. The Kokura Arsenal built eight prototypes for the second round of trials held at the Army Infantry School in 1937, after which the IJA rejected the Nagoya weapon. It identified several problems that required remediation, and a batch of fifty guns was built for operational trials in 1938. After another round of trials in December at the infantry and cavalry schools, the weapon was accepted as the Type 97 Automatic Cannon. The gun has a gas-operated delayed-blowback mechanism in which the barrel and receiver also recoiled to help steady the weapon. Despite reports that it can fire in full-automatic mode, the weapon is semi-automatic only as it lacks a selector to disable the semi-auto disconnector. The Type 97 was the heaviest anti-tank rifle of World War II and weighs ready to fire, minus the gun shield, and including the shield and four carrying handles, handily exceeding its design weight of . It uses a seven-round removable box magazine mounted above the receiver. The gun can fire a dozen rounds per minute.