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Type 3 120 mm 45 caliber naval gun
120 mm bow gun on IJN Yunagi1936.jpg
Bow gun on Yūnagi, September 1936
Type Naval gun
Coast defense gun
Place of origin  Empire of Japan
Service history
In service 1918-1945
Used by  Imperial Japanese Navy
Wars World War I
World War II
Production history
Designed 1914
Variants Type 11 120 mm 45 caliber naval gun
Weight 3 metric tons
Length 5.550 meters
Barrel length 5.4 meter bore

Caliber 120 millimetres (4.72 in)
Action manual
Breech single motion interrupted screw Welin breech block
Elevation -7° - 33°
Traverse +/- 120°
Rate of fire 5-6 rounds per minute
Muzzle velocity 2,707 ft/s (825 m/s)
Effective range 15000 meters

The Type 3 120 mm 45 caliber naval gun was a Japanese naval artillery and coast defense gun used on destroyers and submarines of the Imperial Japanese Navy during World War I and World War II. It's title properly would be written 12 cm/45 3rd Year Type under the same naming system as the 41 cm/45 3rd Year Type naval gun, 20 cm/50 3rd Year Type naval gun, 15.5 cm/60 3rd Year Type naval gun, 12.7 cm/50 Type 3 naval gun and all other Japanese naval artillery. "Third Year Type" (sometimes written as "Type 3") refers to the Welin breech block used on all these guns. It was an indigenous development of the British-designed QF 4.7 inch Gun Mk I - IV, which had been previously produced in Japanese as the "Type 41", under license from Elswick Ordnance Company, part of Armstrong Whitworth. It should not be confused with the later Type 3 12 cm AA Gun developed by the Imperial Japanese Army in 1943 (in Japanese Army convention, "Type 3" refers to its year of introduction rather than the type of breech block used.)

Design and development

Designed in 1914, the Type 3 120mm gun was used as the main armament on Kawakaze, Momi, Minekaze, Wakatake, Kamikaze and Mutsuki-class destroyers in single mountings.

The type was re-designated in the metric system from October 5, 1917, although the Japanese like the Germans, tended to use centimeters rather than millimeters in the official designations.

A re-design in 1922 with a shorter gun barrel and improved horizontal sliding breech-blocks was designated the Type 11 (or 11th Year Type, as were other designs utilizing the same breech design), and was used on submarines and the Ōtori and Chidori-class torpedo boats.

The gun, which was manually loaded, normally fired a 20.3 kilograms (45 lb) High-explosive shell or an illumination shell. After 1943, anti-submarine shells also become available.

Weapons of comparable role, performance and era


  • Bishop, Chris (eds) The Encyclopedia of Weapons of World War II. Barnes & Nobel. 1998. ISBN 0-7607-1022-8
  • Campbell. John. Naval Weapons of World War Two", Naval Institute Press (1986). ISBN 0-87021-459-4
  • Chant, Chris. Artillery of World War II, Zenith Press, 2001, ISBN 0-7603-1172-2

External links

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