Large Caliber Naval Guns
The 8″/55 caliber gun (spoken “eight-inch-fifty-five-caliber”) formed the main battery of United States Navy heavy cruisers and two early aircraft carriers. United States naval gun terminology indicates the gun barrel had an internal diameter of 8 inches (203 mm), and the barrel was 55 calibers long (barrel length is 8 inch × 55 = 440 inches or 36.6 feet or 11 meters).
These built-up guns weighed about 30 tons including a liner, tube, jacket, and five hoops. A down-swing Welin breech block was closed by compressed air from the gas ejector system. Loading with two silk bags each containing 45-pounds (20 kg) of smokeless powder gave a 260-pound (120 kg) projectile a velocity of 2800 feet per second (850 m/s). Range was 18 miles 31,860 yd (29,130 m) at the maximum elevation of 41 degrees. One of USS Louisville’s main gun turrets damaged from kamikaze on January 5, 1945 was removed and taken to the Nevada Test Site and converted into a rotating radiation detector, to collect data on nuclear tests.
Credit to : Matsimus