The 12.7mm Type 1 (1941) was a Japanese aircraft machine gun widely used during World War II and also known as the Ho-104. The Ho-103 was actually a fixed gun and the Ho-104 a flexible gun. It was based on the American .50-caliber M1921 aircraft Browning machine gun but achieved a higher rate of fire by using a smaller, lower velocity Breda (Vickers) cartridge, intermediate in length between the WW II German 13 mm calibre MG 131's 64mm length cartridge, and the long 99mm cartridge of the veteran American M2 Browning .50 calibre gun. Because of this, the gun was frequently loaded with explosive or incendiary ammunition in an attempt to increase terminal effects on aircraft.