Type 3 120 mm 45 caliber naval gun

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 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.

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.

A re-design in 1922 with a shorter gun barrel and improved horizontal sliding breech-blocks was designated the Type 11, and was used on submarines and the Otori and Chidori class torpedo boats.

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

Weapons of comparable role, performance and era

 * BL 4.7 inch /45 naval gun : British equivalent