Type 4 20 mm twin AA machine cannon was an Imperial Japanese Army (IJA) anti-aircraft gun. It consisted of two Type 98 20 mm AA machine cannon. It was introduced in 1944 and approximately 500 to 616 guns were produced.Taki's Imperial Japanese Army: Type 4 20 mm twin AA Machine CannonTaki's Imperial Japanese Army: Type 98 20mm AA Machine Cannon It was mainly designed for use against ground targets, but was only used in an anti-aircraft role.
The Type 98 20 mm AA machine cannon was the most common light anti-aircraft gun of the Japanese military and the IJA used it until the end of World War II.War Department TM-E-30-480 Handbook on Japanese Military Forces September 1944 p. 400.
References Notes
Sources
Taki's Imperial Japanese Army Page: Type 4 20 mm twin AA Machine Cannon - Akira Takizawa Taki's Imperial Japanese Army Page: Type 98 20mm AA Machine Cannon - Akira Takizawa War Department TM-E-30-480 Handbook on Japanese Military Forces, September 1944.