 The original design called for eighteen 5 " / 51 caliber guns. These guns were originally mounted on the Florida- and Wyoming-class battleships, but they found their way into the secondary armament of every U.S. battleship that was built prior to the Washington Naval Treaty. Also, many of the destroyers, submarines, and auxiliaries that were built during this time mounted this gun as their main gun. They fired a 50-pound (23 kg) shell at a muzzle velocity of 3,150 fps (960 mps) and a rate of eight or nine rounds per minute to a range of 18,880 yards (17,260 m) at an elevation of 25 degrees.
