The technical case for retaining 305 mm guns was strong because estimated penetration at 20,000 meters was almost identical to that of the 320 mm alternative. Keeping the smaller caliber promised fewer changes to ammunition supply and loading arrangements, avoided an extended experimental phase, and allowed liners to be replaced more gradually. The political and institutional case favored 320 mm because officers and the public might not understand an extensive modernization that retained the smaller caliber while Dunkerque carried 330 mm guns. A common 320 mm battery across the reconstructed classes also avoided a split-caliber fleet. Commission estimates then weakened the schedule argument for 305 mm by finding that either weapon would take about 22 months to produce and the mountings about 28 months.
Notable Point · 11:04-13:41
Cavour gun caliber pits logistics against morale
The 305 mm versus 320 mm decision turns on ammunition logistics, production time, fleet morale, and how the rebuilt ships would compare publicly with Dunkerque.