6"/53 caliber gun 6"/53 caliber gun The 6"/53 caliber gun (spoken "six-inch-fifty-three-caliber") formed the main battery of some United States Navy light cruisers and three US submarines built during the 1920s. United States naval gun terminology indicates the gun fired a projectile 6 inches (15 cm) in diameter, and the barrel was 53 calibers long (barrel length is 6 inch x 53 = 318 inches or 8 meters.) The gun with side swing Welin breech block and Smith-Asbury mechanism weighed about 10 tonnes and used a silk bag containing 44-pounds (20 kg) of smokeless powder to give a 105-pound (47.6 kg) projectile a
15 cm/45 41st Year Type Japanese designation system for artillery changed from inches "6 in/45 41st Year Type" to centimeters "15 cm/45 41st Year Type". Whether the guns originated in Britain or were built in Japan they still shared the same 41st Year designation. The 15 cm/45 41st Year was constructed of an A tube and wire wound with a protective outer jacket. Ships built in British shipyards for Japan were armed with Pattern GG guns and later Japan produced their own versions under license at the Kure Naval Arsenal. Four different models were produced at Kure which differed in the style of rifling used.