The large oceanic submarines carried a destroyer-sized 4.7-inch deck gun. If destroyers had adopted the 4.5-inch gun earlier, submarine armament might also have shifted to that calibre. This is a logistical counterfactual rather than a claim about what happened. Common ammunition across more ship types could have reduced the variety the fleet needed to manufacture, store, and distribute.
Notable Point · 22:25-23:01
Deck-gun calibre as a fleet logistics problem
Standardizing 4.5-inch weapons across destroyers and submarines could have simplified ammunition supply across ship types.