Calibre decisions began with shipboard constraints. Increasing gun size changed the size and weight of shells, the arrangements needed to move and store them, and the weight that turret machinery had to traverse. Those demands affected how many rounds a ship could carry and how readily the existing supply system could adapt. The Royal Navy's previous experience with 13.5-inch weapons made this step easier to accommodate while still giving Orion more fighting power than the 12-inch generation.
Notable Point · 17:14-19:15
Gun calibre, logistics and turret weight
The 13.5-inch choice affected more than prestige: shell storage, handling arrangements, ammunition supply and turret movement all shaped what a practical battleship could carry.