Hi all, thanks for all the great responses to all my previous posts, rather interesting with all the diverse opinions and comments.

I was just wondering how many people have Brit guns they think are in Proof, when in fact they aren't?

How many people who do not have the proper gauges/tools to measure bbls take the word of a dealer or the Proof Marks themselves as gospel? And for years have been shooting a gun that is out of proof.

And lastly, how many of you would buy an out of proof gun where the WT is good and thick and the bbls are proper, except that the chambers have been let out or some other modification done to the bbls? Please note, IF the WT is good and thick just ahead of the chambers and all throughout the bbls.

Please, don't read into this, I'm NOT buying a gun with this issue. But to be honest, I do have a Purdey that has the chambers let out to 2 3/4" and the WT at the end of the chambers is at .130. And no, I'm not sending it off to have it Re-Proofed, and yes I only shoot low pressure loads in her. She's been a champ for me.

Best!

Greg

Yes, I will and do buy guns out of proof. As you know it is illegal to sell an out of proof gun here in the U.K. but, as with all red tape, there are often simple ways around it. I will only really buy guns that I know stand a very good chance of passing re-proof and have any necessary work done and then submit them for test. Quite a simple procedure here and usually worth the risk if done with some care. I have only ever had one fail which was then re-submitted after some minor work and the next time it passed. Lagopus.....

The overall concern is that guns 'in proof' should be pretty much guaranteed to be safe when used with CIP loads within the proof limits. To this should be added that as far as I know all cartridges for sale in the UK are CIP compliant. Guns that are 'out of proof' MAY be safe enough, but not necessarily.
In your case you understand the issues - and use the gun sensibly. I would do the same in your shoes.

However, if you were to sell it, it might fall into the hands of a beginner, who might end up having an accident.
I would not normally buy an 'out of proof' gun, though it can be done through an RFD (Registered Firearms Dealer) for sleeving or rework for submission for proof.

Incidentally, I think that it is a great shame that so many people lengthen the chambers. English guns were built often to relatively slim wall thickness margins - to save weight which was always a high priority. I understand that 2 1/2" cartridges are readily (if not quite so widely) available in the USA. Once the gun is chambered to 2 3/4", the risk that someone will use an inappropriate load seems to me to be increased.

I would consider purchasing a British gun with lengthened chambers, which has not been re-proofed, if, as you say, the forward end of chamber walls remain thick enough.

Sure, I would much prefer it be in proof. But If I REALLY like the gun, I must admit that I would consider it.

I am able to measure wall thickness, but that brings up a rather important question...

What is the minimum acceptable chamber/cone thickness for the various bore sizes?

For a 12b, a 20b and a 28b? What about for the .410?

And by acceptable, I mean safe for use with 2 1/2" RST light loads?

Thanks

I would consider one that has had the chambers lengthened IF it was a nice gun. With that said I would understand I would take a beating on the back end when I sell it.
My English guns came from reputable dealers and I have checked them for proper wall thickness and chamber length.
But I will take that old out of proof Purdey of yours off your hands.

Measured wall thickness is more important than proof, end of story. However, extended chamber length above proof, is a sign that the gun has been in the hands of an idiot, so very careful measurements of wall thickness should be taken before purchasing the gun.

Redoak: please see http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=361965#Post361965

but be aware that the CIP 'standard steel' is 4140 or better. We should soon have an idea of the tensile strength of some more than 100 years old segments of pattern welded steel, which may or may not contribute anything meaningful to the conversation

Also, the CIP recommendations did not include the wall thickness along the length of the forcing cone. Because the angle of the cone usually exceeds the angle of the OD of the barrel, the wall thickness of all the ORIGINAL cones that I have measured has been greater than the end-of-the-chamber wall thickness.
I would be interested in the experience of others however.

Another victim of chamber lengthening, honing, and light magnums

I have only bought one British double that had the chambers lengthened or messed with - and I bought it with that unknown. I later returned the gun after I found out that the chambers had been lengthened and there was a problem. I try to stir clear of any guns that have had the chambers lengthened.

Would I consider buying a gun that the chambers were lengthened - yes. But only if I felt I had to have the gun for some reason, and I knew who did the work in the case of it being a USA based gun and after a thorough inspection by Kirk Merrington.

For me, there are too many good guns out there to bother with one that has issues.

Why is "who did the work" an issue when metal is being removed, regardless of who did it? Metal should not be removed, and Drew's picture tells us why. "Proof" in the US is all about wall thickness, not government intervention.

Hi Drew,

Thank you for the information and for the link. I realize now that I had seen that thread, but I had forgotten where.

And I appreciate & note your caution re: 4140 or better. Do you have any idea how fluid steel on a mid-grade, mid-1930s vintage Birmingham boxlock would compare? Probably not very well, would be my guess... But maybe I would be pleasantly surprised.

I see the end of chamber measurements that I was looking for (for this CIP 'standard steel') are .079" for 12b and .075" for 20b. Does it follow then that it might be slightly less for a 28b, and even a bit less yet for the .410?

Chamber pressure is actually higher for 28s and .410s, and at least the German proof house recommended more wall thickness for 24s and 28s. Most .410s have pretty stout barrels.

The proof test for a 3" .410 is 5 TONS per square inch.

The key difference of course is public safety. Selling an out of proof gun being illegal is to save the unwary from the unscrupulous.

If you have the tools and knowledge to make a judgement call, by all means do so.

However, note they proof makes no mention of wall thickness. It is all about standing up to the test. If the walls are 10 thou but very strong material, they may well pass, but they could be 50 thou or poor quality or defective steel and fail.

Without attest, it is a guess, some will be more educated guesses than others.

Proof divulges flaws in the gun barrel which just pure wall thickness tests don't. Wall thickness is of course a good guide but not definitive.

Eightbore, Proof isn't Government interference as it was set up by the gun trade to prevent badly made guns being sold to the public and to protect the gun trade itself. They make the rules and enforce them. Lagopus.....

I may be mistaken, but I suspect your rules of proof assisted the confiscation of handguns. They aren't everyone's cup of tea, but you have some of the best engravers in history that can no longer create their timeless art on that form of firearms.

No! The proof laws played no part in the confiscation of hand guns here in Britain
It was an act of Parliament voted on by the members of parliament and given the final sanction by the members of the House of Lords.
To some people it may be misguided and stupid but that is a parliamentary democracy for you, some things you agree with and others you do not but with democracy comes the responsibility to accept being outvoted.

I think the attitudes about and politics involving guns and government will remain vastly different between the countries. And I have no doubt a national proof house here would attract the wrong politicians, and become a battle ground for control.

as it is - I carry a bore and wall thickness gauge and hope that along with a detailed visual inspection it will give me some not over rated confidence. When purchased based on the above, antiques normally go to a gunsmith I trust just to be sure.

The issue on this side of the pond is that back before WWII, we stopped making short-chambered guns. 12, 16, 20, 28 all became 2 3/4" standard. For some time, the ammo makers continued making short shells for the short-chambered guns. But that stopped not long after the war. Result: Gunsmiths thought the solution to a short-chambered gun with only 2 3/4" shells available was to lengthen chambers to 2 3/4"--even though the 2 3/4" shells were loaded to a service pressure standard about 1,000 psi higher than the short shells.

For the most part, that worked relatively well. American shotguns, especially 12's, are heavier in general than British game guns--which meant there was metal to spare. It didn't always work so well with smaller bores, especially very light ones with thinner barrels or with receivers that were also made lighter, but they were a minority. And we have no national proofhouse, nor do we have a law that says a gun can't be legally sold following significant material alteration. It's strictly a case of "caveat emptor". So we have a lot of vintage side by sides with lengthened chambers. Probably a good idea to check barrel wall thickness, on small bores in particular, on which the chambers have been punched. And thanks to the interest in vintage guns, websites such as this, and publications such as Double Gun Journal, more Americans now understand those issues. But that does not help replace the removed metal in all of our formerly short-chambered guns that are now 2 3/4".

In proof or out of proof is only a state of being or a technical status and even that does not exist in the US. Means notheing here because 99.9% of buyers do not understand in or out of proof. Remember the 20 ga. Clark that Tony Treadwell had reproofed, that passed proof and then developed a bulge or split in less than a box of shells. Those were proper shells and the gun had just passed proof so just because it passes proof there is not absolute guarantee that it is going to last forever. Shame because that was a very nice looking gun when he got done restoring it.

Ever wonder why is there no Proof house in the US? Because we are the worst people for that type of protection. In the US people tend to think that a proof type test should guarantee something is safe and will last forever. If it fails the first thing a person over here wants to do is find out who to blame, because it can not be his own fault, and then figure out if they have a legal claim. That is why a proof house system would never last over here. Every failed gun would have some lawyer looking at a potential claim against the proof house and if that is not possible then a class action suit against it for all the failures. The thinking would be the proof house test is not high enough pressure so it does not detect all potential failures in advance and therefore the proof house is not doing its job.

The second problem is that reloading is too popular here. Too many of us reload and we all know how loose quality control can get in some people's reloads. Ever shoot a round of skeet with a fellow with squib loads? Every wonder if he got the missing powder into another shell. Ever shot behind someone who had a shell with just a little too much powder in them? If his gun fails he denies ever using reloads. Then he would seek legal action against the proof house if his gun was proofed in the US. They already try to go after the maker if they can.

A US proof house would be just be another soft, easy target for them. Shame really because I think there is a real nich market for a proof house over here. How many here would welcome a proper proof house here that could reproof a gun to a know standard? I would. A proof house is not an absolute slam dunk for long term safe use but it would be welcome confirmation that a gun is in basic shape for safe use. Right now we just go by looking, measuring and hope we have not missed anything that will come back to bite us on the rear end.

Just a reminder. H.P. White Laboratory, Inc. in Maryland will proof Twist or Damascus barrels for $500 to a pressure of 20,000 psi, or the pressure desired, and has allowed at least one owner to watch the procedure
www.hpwhite.com
http://www.hpwhite.com/uploads/file/100-00.pdf

I recognize that one must value the gun, or one's digits, substantially in order to justify the expense.

BTW: It was the hope of Major Sir Gerald Burrard that NDT would eventually be added to Proof Testing; writing in the Second Edition of The Modern Shotgun, 1948 in “The Protection Afforded By Proof”:
The best plan of all would be to incorporate in Provisional Proof one or more of the methods of “Crack Detection” which have been developed so successfully since about 1935. X-rays are used regularly in all big steel works for the detection of flaws in steel, but it is at present doubtful whether the results are always quite so definite when examining a tube as they are in the case of flat plates. Magnetic and Fluorescent Crack Detection has proved very satisfactory and is comparatively cheap and simple.
It may well be that the rapid advance of scientific research may open out new and better methods for the detection of flaws, and it will be a tragedy if the hands of the Proof Authorities are tied by an Act of 1868.

Working on that

Thank you for a good and clear explanation of the thinking 'your side of the water'.

It is interesting that my favoured clays load in a light old 12 is less than might regularly get used in a 20 in the USA. (3/4 Oz).

Geez Drew, $500 for proof test; it's only about £20 a barrel here. Lagopus.....

The problem for us, Lagopus, is getting the gun there and back. By the time that happens, it's a lot more than $30-35.

The only British guns I have are all more than 100 years old with black powder proofs. To be totally honest I don't want them reproofed.