doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 13 bore proof question, 1867 Purdey

This may have already been covered somewhere but I cannot find a definitive answer, maybe there isn't one.
First, let me state what I believe to be correct information, (please correct me if I am wrong).
Bore sizes were stamped on the barrels, in fractions, starting in 1887. ie. 13/1, 12/1, 13, 12, etc.
As well the bores were measured using specific plugs, ie. if a 12 bore plug of .729 did not fit a bore of say .728, they would stamp it 13/1 and not 12 and so on.

However, in 1867 for instance, before fractions were introduced what range could a 13 bore stamp fall into....?
If a .729 plug would not fit the .728 bore and since fractions were non existent at the time would it be marked 13........?

any info would be much appreciated.
thank you in advance.

!
1st ? .710-.729
2nd ? yes 13 it would be

The 710 figure may be off by a thou or two but I don't have 1954 proof rules in front of me.

Thx Hugh

That was my thinking, just wanted someone more knowledgable to confirm.
So my Purdey that is stamped 13 and measures .730 could very well be in proof and likely is.

As well as my 1885, Greener stamped 13 and measures .735.
Of course everything else has to conform to proof as well, that goes without saying.

cheers

A gun proofed at 13 would be out of proof at .719" as that is the nominal 13/1 size.Hth.

Imperdix, actually you are wrong. The proof rules for guns proofed before the rules changed in 1887 (which can be confirmed by the presence or absence of the Diamond introduced with the fractional markings) still apply if the gun hasn't been reproofed. So a pre-1887 13b is in proof right up to one thou short of the 12b measurement of 0.729. The proof authorities don't like it but that is the law.
So in essence: a gun is judged to be in proof by the rules current at its last proof test.

Well I never,would you sell such a piece ? I can well believe the Proof house not being impressed that such guns slip through!!!!