The design board issued a basic outline for the Montana class that called for it to be free of beam restrictions imposed by the extant Panama Canal, be 25% stronger offensively and defensively than any other battleship completed or under construction, and be capable of withstanding the new "super heavy" 2700 pounds armor-piercing (AP) shells used by US battleships equipped with either the 16-inch/45 cal guns or 16-inch/50 cal Mark 7 guns.