British gun calibre choices and nine-gun salvos

What happened to the British 18-inch turret?

The twin 18-inch mounting appears to have remained too immature for a readily available ship installation. Infrastructure and design constraints pushed the G3 battlecruisers toward nine 16-inch guns instead.

In this interpretation, the British preference for 45-calibre guns balanced performance against weapon weight, mechanical reliability, and operation in difficult weather. The unfinished 18-inch twin-turret work appears to have lacked the engineering maturity and infrastructure needed for a ship installation. G3 could combine the desired speed, armour, and armament within existing infrastructure only by reducing gun size or accepting twin 18-inch mountings. Nine 16-inch guns also provided a useful ranging-salvo pattern. Twelve guns are described as ideal, while nine became a practical American arrangement because the battery divides cleanly into ranging salvos.