The capital-ship gun proposal starts with a 16.5-inch barrel fitted with an extra-thick liner that reduces its bore to 16 inches. A normal liner could restore the larger calibre in war. Alternatively, coastal batteries using matching larger guns could provide replacement barrels and ammunition already held ashore. Common manufacture would supply an economical explanation for the barrel's dimensions. The argument turns on the calibre actually carried in peace, while the larger wartime outfit remains a prepared option.
Chapter · 27:41-31:03
Using gun liners to preserve a larger wartime calibre
A thick liner could make a 16.5-inch barrel fire a treaty-compliant 16-inch shell while preserving a later conversion option.