Mount 55 (Secondary Battery): 5 inch 38 caliber Mk 12 gun.
Gun Layout: Mk 28 Mod 2 twin enclosed mount. The original design was 10 twin mounts (two guns in each mount), but the number was reduced to 6 twin mounts duing the 1980's.
Gun Elevation: Both guns raise and lower together from -15º to +85º.
Rate of Fire: 15 rounds per minute but could surge up to 21 depending on the level of crew training.
Effective Range: 10 miles surface, 7 miles (37,000 feet) altitude anti-aircraft.
Ammunition: Semi-fixed – meaning the 55 lb projectile is separate from the 28 lb brass or steel alloy powder case. Each mount magazine held 595 projectiles and 595 powder canisters.
Gun Crew: 27 in the mount and upper handling room plus personnel in the magazine.