The Type 10 or 12 cm/45 10th Year Type naval gun was a Japanese 120 mm calibre dual purpose anti-aircraft and coastal defense gun used during the Second World War. It was derived from the 12 cm/45 3rd Year Type naval gun. The Type 10 number was designated for the year the gun was accepted, the 10th year of Emperor Taishō's reign, 1921 in the Gregorian calendar.
It served as the secondary armament on a number of Japanese aircraft carriers and cruisers and as the main armament on smaller ships, in single or twin mountings.
Despite mediocre traverse and muzzle velocity, the 12cm Type (Taisho) 10 was widely used throughout the Pacific since it was relatively simple to produce, threw a powerful shell, and did not require external power (making it easier to emplace at remote sites). By the end of the war 40% of the naval AA units in homeland Japan were equipped with this weapon as well.
Description
The weapon was originally designed for ship use and was produced in large numbers. The gun was also adapted for land use as a dual-purpose gun. It was one of the few Japanese cannons that could readily handle more heavily armored allied tanks such as the sherman. The barrel was of autofretted mono-block construction and was held in a sleeve cradle mounted on a pedestal mount which permits 360° of traverse. The gun uses a hydro-spring recoil mechanism attached to the sleeve cradle and there are three recoil cylinders located on top of the breech with the two outside cylinders housing the recoil springs, and the center cylinder housing the hydraulic recuperator.