doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com In Proof means ?

I work in the pressure vessel industry, and I would substitute the word 'terrifying' for 'compromised.'

Six thou' is roughly two sheets of cheap photocopier paper thick.

To paraphrase Ronald Reagan, Trust but measure. Assume nothing until you know.

I recall reading (somewhere) that with some 12 ga. 2' doubles it was believed(speculated?) that barrels were proofed in the white and when finished by the gunmaker, the barrels' exteriors may have been further struck to reduce weight which would have left bore measurements intact. I'd verify the MWT as it does sound like a misprint. Two pieces of copy paper stacked together measure .007". Here's an article that discusses the 2" 12 ga. guns and it mentions wall thicknesses with one gun measuring .012".

https://shootingsportsman.com/short-shell-12-2-guns/
Gil

Jon, you're referring to Lyalvale shells. They are unpleasant, for sure. The late Bill Hanus was hawking them at one point. Sent me some to try out. Back then I often shot skeet with a lawyer friend who owned a really nice Lebeau Courally boxlock. I handed him a couple Lyalvales on Station 1: "Here you go, Bill . . . give these light British loads a try!" He only shot one of them and had some very unkind words for me.

I'll throw my thoughts and experiences in on this one.
1st Drews pressure data. The SAPL after 12/50 should alert us to something unique to this pressure. A click on the link provided Shows cartridges 12/50 with a note "FUN tir cartridges are a 12/50 caliber "gum-cudgel" type cartridge that can only be used in products from the SAPL Co. I translate gum-cudgel as Rubber Club. They look like non lethal defense products firing a rubber ball.
2nd GLS comment Pretty much all new production guns are finished "In the White" with some polishing afterwards.
3rd Ted S/Imperdix" comment are I'm sure the answer.
A wall thickness survey before and after the thin spot,particularly adjacent to but up against the ribs would most likely tell what the original thickness was.

I once sold a 1935 H&H 12-2" Dominion back to H&H New York.So as not to waste time doing the Wall Thickness song and dance I advised Guy D. The wall thickness is only .014" each Barrel. 9" back from the Muzzle. Without looking up from the gun he said "Don't worry that's the way we made them!
Hope some of this helps. It's a Sleever for sure, good lock finding suitable tubes.

This statement is not correct. If the bore of a gun is opened or honed to an inside diameter. 008" larger than its' original proof bore diameter, it will still be in proof, as stated. But the barrel wall thickness will not be reduced by .008". On average, the wall thickness wiil only be reduced by .004". In this example, the original wall thickness of .025" will not be .017" after reaming or honing, but more like .021". That's a significant difference.

I am curious about the location of the area in the barrels mentioned that have a .006" MWT. I agree with Ted and Fudd about them being both very compromised, and scary too. I don't want even 1000 psi of powder gasses abruptly escaping anywhere near my eyes or fingers. There are too many perfectly sound guns available to risk using one with barrels that are soup can thin.

Yes Keith you are right. But the point is being in proof means nothing as to being safe. Many here, think being in proof is good enough. The gun listed above is clearly in proof and has a wall thickness of .006. I doubt anyone here would be happy to find out their new purchase has walls that thick and I doubt anyone who sees what .006 looks like will shoot it. I doubt a .006 tomato stake would last long.

A gun passing proof with MWT of .006 does not make sense to me. Something doesn’t jive; there’s more to this story. I would think such a gun would be summarily rejected by the proof house regardless of whether it survived the proof loads. The authorities responsible wouldn’t be so hidebound as to pass a gun that was obviously unsafe, would they?

Hugh--Glad you chimed in! I remember looking at a 2" 12 in your shop and discussing the fact that barrel walls often left the maker on the thin side. And I think I recall discussing the lighter proof that was allowed on 2" 12's under the 1954 rules with you.

eeb, this gun did not just pass proof. I am sure it was proofed with barrels thicker than .006. Holt's has clearly stated the barrels now are .006 and that it is in fact still in proof and legal for them to sell. How is that possible? Proof does not include a wall thickness determination. The proof house does not measure wall thickness. They give you a yes or no answer to does this gun pass a proof load with out issues.

Perhaps it had a dent that was raised and struck before reblacking. I bet that it was a dent raised which is the root cause instead of honing to death. SO it might be a localized issue but where is the issue. Perhaps it has been reamed out to clean up pits down the bore, but the first 9" still have some metal left so it is still within .009 of what it was proofed. IF the original barrels were .014 and it has been honed until they are now .006 they could still be in proof. Just not anything I want to buy and certainly nothing I wish anyone here to use thinking being in proof means safe to fire. Measure everything and then decide what your level of risk you want to take. A .006" spot an inch from the muzzle might be a judgement call but not one just under your left hand. That is a accident waiting to happen.

IN PROOF MEANS NOTHING CERTAIN BEYOND LEGAL TO SELL. IT IS NOT A GUARANTEE OF SAFETY MANY ASSUME. END OF LARGE PRINT.