The 5-inch/38 caliber Mark 12 is a naval artillery gun used by the United States Navy. It features a 5-inch diameter projectile and a barrel length of 38 calibers, meaning the barrel is 190 inches long. This gun is designed for both anti-ship and shore bombardment roles, providing versatility in naval operations. Introduced during World War II, the Mark 12 has been mounted on various ships, including destroyers and cruisers. Its design allows for a high rate of fire and effective range, making it a reliable weapon for engaging surface targets and providing naval gunfire support to ground forces.