5-inch/51-caliber gun
5"/51 caliber guns initially served as the secondary battery of United States Navy battleships built from 1907 through the 1920s, also serving on other vessels. United States naval gun terminology indicates the gun fired a projectile 5-inch in... Wikipedia
Barrel length: 255 in (6,500 mm) bore (51 calibers)
Breech: side swing Welin-type
Caliber: 5 in (127 mm)
Effective firing range: 17,000 yd (16,000 m) at 20° elevation
In service: 1911–c. 1947
Maximum firing range: 20,142 yd (18,418 m) at 45° elevation (World War II ammunition)
Rate of fire: 8-9 rounds per minute