Type 98 20 mm AA Machine Cannon

• Name — Type 98 20 mm anti-aircraft machine cannon • Origin — Empire of Japan • Design Date — 1933-1938 • Type — Autocannon • Is Ranged — yes • Is Artillery — yes • Service — 1938–1945 • Used By — Japan, Indonesia • Wars — World War II Indonesian National Revolution First Indochina War • Number — 2,500 of Type 98 and approximately 500 of Type 4 (an alternate source states 3,241 Type 98 and 548 Type 4 units produced) • Weight — 373 kg • Part Length — 1.4 m L/70 • Cartridge — 20×142 mm • Cartridge Weight —.14 kg • Caliber — 20 mm • Action — Gas operated • Rate — 300 rpm (cyclic) 120 rpm (practical) • Velocity — 830 m/s • Max Range — 5.5 km (horizontal) 3.5 km (ceiling) • Feed — 20 round box • Carriage — Two wheeled split trail. • Elevation — -5° to +85° • Traverse — 360° • Illustration — A drawing of a Type 98 20 mm gun from a US Army field manual

The Type 98 20 mm AA machine cannon was the most common light anti-aircraft gun of the Japanese military. The Type 98 designation was given to this gun as it was accepted in the year 2598 of the Japanese calendar (1938). It entered service that same year and first saw combat in Nomonhan. It was used until the end of World War II. About 80% of the Imperial Japanese Army light AA guns were Type 98s. The gun could be emplaced in about three minutes by an experienced crew or fired inaccurately from its wheels. It was also used as an anti-tank weapon, it was considered to be robust, light, and easily portable. This weapon and its variants were based on the French design of the 13.2 mm Hotchkiss machine gun of the 1930s, which the Japanese forces had bought and further developed at home. The Type 98 was also one of the two armament options for the IJA's Submersible gun mount Model 1.

• Type 100 armour piercing tracer. Weight 162 g projectile and 431 g complete round. • Type 100 high-explosive tracer (with self-destruct). Weight 136 g projectile and 405 g complete round with 890 m/s.

Two of the guns mounted together formed a variant known as the Type 4 20 mm twin AA machine cannon. Approximately 500 to 548 of these guns were produced.