Yep. Eccentricity happens.

http://pic20.picturetrail.com:80/VOL.../409066906.jpg

Roger that Drew, and especially if you send a gun to the wrong gunsmith to mess with the chokes. I can unfortunately attest to that.

Question on proofing: When barrels are proofed, they fire "proof loads" through them. From what I have read a proof load is equivalent to twice the pressure of a "normal" load. Am I correct? And do they only fire one of these proof loads or do they fire multiple proof loads through the barrel being tested? What do they look for? I assume they measure the barrel to see if the chamber expanded ... do they have some other way to know if the barrel is safe? It can't be that they just shoot it and see if the barrel blows up -- I hope it's more scientific than that! That's why I don't think tying the gun down to a tire and pulling the trigger with a long string really tells you anything. I'd like to understand more about this topic -- especially what effect repeated firing has on the barrel. Which is a better test? One heavy proof load or multiple firings of heavy loads. How do we know that our guns are not getting weaker and weaker the more we shoot?

a proof load

http://gunproof.com/Proofing/proofing.html

correct, its not about seeing if the barrel blows up, there are many pre and after proof measurements that are taken and compared to make sure no changes occurred

a single large load, but be aware there are no proof laws/standards in the US

each maker had their own procedure

Just as a precaution - two years ago i sent a set of Parker fluid steel barrels to Parker Bachelder to measure them for safety and he got back to me a few weeks later saying he believed them to be safe. I said Fine, but what were the wall thicknesses incrementally along their lengths and circumferentially, just so that I would know? At that point he told me that he didn’t know but inside measurement subtracted from the outside measurement showed plenty of thickness....
I asked, But what were the thicknesses in thousandths in the incremental locations that I had asked before? At this point (again, two years ago) he admitted they didn’t have a wall-thickness gauge....
They may have since bought one - I don’t know.





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Jeff Kuss graciously shared an explanation from Parker Bros. of the testing protocol. It's here about 1/3 down
https://docs.google.com/document/d/1...UOZEFU/preview
It is important to understand that the "rough forged tubes", both damascus and fluid steel, sourced in Belgian by all the U.S. makers were also proved.

A Parker Service and Proof Load table was published in the 1930s and reproduced in The Parker Story p. 515. 12g 2 3/4” shell Service Pressure is 10,500 psi. Definitive proof used 7.53 Drams Black Powder and 2 oz. shot with a pressure of 15,900 psi. The pressure was no doubt measured using LUP and modern transducer values would be 10-14% higher, or more than 17,500 psi.

LTC Calvin Goddard reported the same numbers in “Army Ordnance”, 1934. He wrote that Parker followed the SAAMI standards of that period: 13,700 psi proof, 9500 psi service for 2 5/8” chamber; 15,900 psi proof, 10,500 psi service for 2 3/4” chamber (by LUP) + 10-14% for modern transducer measurement.

Thanks -- Interesting site even though very vague on the details of how a gun is proofed.

“Birmingham Gun Barrel Proof House at Work”, 1951
https://www.youtube.com/watch?v=f3aHnxsj7y8

They did. When I picked up my refinished Dam barrels in June, 2018 I had them take measurements.

I hesitate to point this out, but a Manson Wall Thickness gauge is $110 at Brownells (about the price of a flat of cartridges). It comes with instructions. Anyone who seriously collects old double guns ought to have one of their own. And use it.

https://www.brownells.com/gunsmith-t...prod20463.aspx