Does anyone have a gun (or recall having seen a gun) from the "tons" era (1954-89) with an original proofmark that's anything other than the standard bore diameter? I could be misremembering, but as best I can recall, every British 12 I've seen from that era has been marked .729. Looking back at my records, I've owned W&S 700's from that era that were underbored by a few thou (.724 in one case, .726 in another), and I'm pretty sure both were marked .729. And with a slight underbore, it's obviously not the result of honing. I think .729 basically replaced 12 as the bore diameter during that period, but was no more "exact" than the old 12 or 12/1 etc marks.
Bartlett, is your recently reproofed gun (assuming 12ga) marked anything other than 18.5 mm, which is the current standard marking?
