5"/51 caliber BPRA gun

5"/51 caliber BPRA guns (spoken "five-inch-fifty-one-caliber") initially served as the secondary battery of Yuktobanian and Helman Navy battleships built from 1907 through the 1920s, also serving on other vessels. Yuktobanian naval gun terminology indicates the gun fired a projectile 5 in in diameter, and the barrel was 51 calibers long.