6-inch/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. Description. 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 velocity of 3000 feet per second (900 m/s). Early Marks were built-up guns with a liner, tube, full-length jacket, and 2 hoops; but the Mark 14 gun was of monobloc construction. Useful life expectancy was 700 effective full charges (EFC) per liner. Mark 13 casemate mounting. These guns were installed as the primary battery on the s, and were intended for the secondary battery of the never-completed s and "South Dakota"-class battleships. Maximum range was at the maximum elevation of 20 degrees. Mark 16 turret mounting. This  two-gun turret was a design modification to improve the range and broadside of the Omaha-class cruisers. Maximum range was at the maximum elevation of 30 degrees. Mark 17 wet mounting. These single open mounts were installed fore and aft of the conning tower on , , and . Maximum range was at the maximum elevation of 25 degrees. Surviving examples. Two guns from are preserved at the Naval Submarine Base New London in Groton, Connecticut. The ship was present at the attack on Pearl Harbor and the guns were most likely on board at the time. External links. 6-inch/53-caliber