doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 11ga chamber dimensions

Binko,
English guns proof tested and stamped 11,11/1,10,10/1,10/2. were all chambered as 10G; no size is given in the rules of proof for 11G chambers.
The same Logic applies in other gauges. We see many vintage 12G English guns that were proof tested and stamped 13G but in every instance the guns are chambered as 12G. there being no 13G chamber sizes in the rules of proof.
I have seen 12G guns with bore diameters up to.750 which is the maximum diameter for a 12G proof tested and marked 12/1
It might well have been legal to proof test a 12 G gun bored .729 as an 11g provided that the gun with stood the 11G proof test. Suggest that you contact the Birmingham Proof House for advice.

Here's what is stamped on the barrels.

Binko;
The left barrel was stamped by the proof house as a 15ga (.677) & the right one as a 14ga (.693). 13ga would be .710" & 12ga .729". This gun was proofed prior to 1887 when the chamber mark was added & at this point no intermediate sizes were marked. Each mark could mean the diameter was somewhere from the designated diameter for that gauge up to just under the next larger gauge. The actual size was not measured but plug gauges of the sizes were simply tried in the bore & the barrel stamped according to the largest that entered to the specified depth.
Another thought comes to mind. Throughout the muzzle loading days & on into early breech loaders before choke boring became rather common bores were gaged from the muzzle. This gun may well have been an early choke bored gun, but was still gaged from the muzzle.

Thanks Miller, surely strange how they did things back then.

binko

binko,
The proof marks on the barrel of your gun indicate that the original calibre of the gun was 14G. Many of these vintage 14 bore shot guns,[for which at one time shells were available], were re;bored to 12G by unskilled gun smiths. Hence the odd- ball chamber size you have encountered. In my opinion 10/11/12G proof or chamber size was never applicable to your gun at the time it was proof tested.