Ho-103 machine gun

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Ho-103 machine gun
12.7 mm Ho-103 machine gun on display at the Steven F. Udvar-Hazy Center
TypeMachine gun
Place of originEmpire of Japan
Service history
Used byImperial Japanese army
WarsWorld War II
Production history
Produced1941 to 1945
Mass23 kilograms (50.7 lb)

Cartridge12.7x81mmSR [it] Breda[1]
ActionRecoil operation
Rate of fire900 RPM
400 RPM (synchronized)
Muzzle velocity780 m/s (2,600 ft/s)
Feed systemBelt

The 12.7mm Type 1 (1941) was a Japanese aircraft machine gun widely used during World War II and also known as the Ho-103.[2] It was based on the American .50-caliber M1921 aircraft Browning machine gun.[1]

The Ho-103 achieved a higher rate of fire by using a smaller, lower velocity Breda (Vickers) cartridge, intermediate in length between the WWII 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.


The Type 1 was produced in two variants. The Ho-103 was used in fixed installations, while the Ho-104 was used in flexible installations.[1]


The 12.7x81SR allowed the Type 1 to fire at a rate of 900 RPM, but the poor suitability of the Browning action to synchronization reduced the rate of fire to 400 RPM in synchronized installations.[1]



  • Rottman, Gordon L. (2010). Browning .50-caliber Machine Guns. Oxford, UK: Osprey Publishing. ISBN 978-1849083300.