doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com British Proof And Pitting

I am interested in a British gun that the seller indicates has "marks" in the bores, but that the gun is still in proof.

Doesn't English proof place some limitation on pitting in the bores? Can someone help me understand how (or if) that relates to the pitting depth or severity?

No expert, but it sounds like it might fail the view portion depending on the severity if submitted for re-proof:

"�View� is a visual inspection by the Proof Master. If he thinks the barrels not sufficiently tight on the action, or he notices dents, pits or other faults, he will reject it as unsuitable for proof. If he considers it in good enough condition, it passes �view� and goes on to be submitted for �proof�."

http://www.vintageguns.co.uk/articles/proof-law/

The Birmingham Proof House requires removal of pits prior to re-proof http://www.gunproof.com/Proofing/proofing.html
"Proof regulations require that shotgun barrels shall be 'struck-up' and smooth and that insides shall be clean. Pitting should be removed so far as is practicable, bulges knocked down and dents raised."

If the original bore was .729" it may "still be in proof" if honed to less than .740" (12/1). "Still in proof" does not necessarily establish the integrity of the barrels.

Drew,

Could you please explain the meaning of the numbers in parenthesis (12/1) in your last post?

Thank you

I'll let someone who actually understands British proofmarks
http://books.google.com/books?id=lvBk8df8PjUC&pg=PA139&lpg



So a bore between .729" and .739" (I think 18" from the breech?) would be marked '12', and if marked '12' would still be "in proof" if honed up to .739" (I think)

This is correct, except that it is 9" from the breech. It was done with a plug gauge. I quote from the 4th edition of the 'Notes on the proof of shotguns and other small arms' "At proof if a plug gauge of 0.729" diameter (but not one of 0.740") will enter the bore to a depth of 9", that barrel is at present marked .729" and under the 1925 Rules of Proof would have been marked 12 - and so on for the other bore sizes"

Whether this is 9" into the barrel strict, or barrel plus chamber - I believe is the whole assembly measured from the breech face.

Thank you for the clarification John...and it was in English

Whether a gun is in proof is simply a matter of whether the bore diameter has been enlarged beyond its stamped range. So if it is marked 12 it has to be between 0.729" and 0.739".
Also a gun can be taken out of proof by significant alteration of the barrels or action, eg. fitting of interchangeable chokes, conversion to ejector, weld repairs to the action etc.
Pitting, thin walls or poor jointing does not take a gun out of proof how ever bad they may be. Unsafe maybe, but not out of proof.
When a gun is sent up for proof, the proofmaster takes a view as to the safety of the barrels. If he doesn't like the amount or location of the pitting, he may fail it at view and return it for further work.
However, he may allow a gun with significant pitting to go through to the actual proof firing if he feels the gun is basically safe.
I have had guns pass proof with some pitting but I have also had guns fail with only a hint of rivelling.
There is very little apparent logic to the process in borderline cases.
And John is correct, the measurement is 9" from the breech face.

Here is a Birmingham Proof House inspection certificate from the 1970s for my Purdey 12 bore side by side, at that time you could send barrels for view inspection and report. Unfortunately they do not provide this service today so I have been informed. I hope you can see all of the relevant figures for bore size depth and limits.

note that the "Between sizes are the average between two adjacent gauge sizes with decimal dropped to 3 places, not rounded. In the larger bores you take the difference between two adjacent gauges, divide by 3 & drop to 3 decimal places. Add to the smaller gauge once for the /1 size & twice for the /2 size.