 The gun was also mounted on pre-World War II battleships and aircraft carriers until replaced by the standard dual-purpose 5"/38 caliber gun, which was derived from the 5"/25 and was similar except for the barrel length.Guns removed from battleships were probably converted for submarine use by late 1943, while a purpose-built variant for submarines was available in mid-1944, and was widely used by them.United States naval gun terminology indicates the gun fired a projectile 5 inches (127 mm) in diameter, and the barrel was 25 calibers long (that is, for a 5" bore and a barrel length of 25 calibers, 5" x 25 = 125", or about 3.2 meters).