12 cm/45 3rd Year Type naval gun

12 cm/45 3rd Year Type naval gun was a Japanese naval gun and coast defense gun used on destroyers, and torpedo boats of the Imperial Japanese Navy during World War II.

Design and development
The 12 cm/45 gun designed in 1895 was an indigenous variant of an Elswick Ordnance Company export design known as the Pattern Y. The Japanese designation was the "Type 41". Later in 1921 the 12 cm/45 gun was used as the basis for a high-angle anti-aircraft gun, designated the 12 cm/45 10th Year Type. The "Third Year Type" refers to the Welin breech block used and this should not be confused with the later Type 3 12 cm AA Gun developed by the Imperial Japanese Army in 1943. In the Japanese Army artillery naming system, "Type 3" refers to the year of introduction, rather than the type of breech block used. When used in naval applications, it was mounted in a shielded barbette, as shown.

A re-design in 1922 called the 12 cm 11th Year Type naval gun (Model 1922) with a shorter gun barrel and a horizontal sliding breech-block was used on submarines and torpedo boats. The 12 cm/45 was manually loaded and fired a 20.3 kg high-explosive, an illumination shell or after 1943 an anti-submarine shell.

In addition to its shipboard role it was widely deployed as a coastal defense gun for Japanese bases in the Pacific and was one of the more common types found by Allied forces.

Naval Use

 * Chidori-class torpedo boat
 * Etorofu-class escort ship
 * Hashidate-class gunboat
 * Kamikaze-class destroyer
 * Kawakaze-class destroyer
 * Minekaze-class destroyer
 * Momi-class destroyer
 * Mutsuki-class destroyer
 * Shimushu-class escort ship
 * Tsukushi-class survey ship
 * Wakatake-class destroyer

Weapons of comparable role, performance and era

 * BL 4.7 inch /45 naval gun: British equivalent
 * 5"/51 caliber gun: US Navy equivalent