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#616891 07/20/22 10:59 AM
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KY Jon Offline OP
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We hear the term in proof and think that says it all. It does not. One of the 2” doubles on the upcoming Holts SealedBid auction tomorrow, has a barrel which is .006” thick I understand. The 2” guns were struck extremely thin to keep their weight down when made. Originally they were proofed at 2” but now I understand they are proofed at the same proof pressures as 2 1/2” guns. A much higher proof level. Lot number 5855C 2” non ejector FP Baker. Walls at .017 and .006. Still in proof otherwise could not be sold except for sleeving. Do not think “in proof” says it all.

So again proof is not a guarantee of being absolute safe to shoot. You still need to measure and know the wall thickness. They do not tell you where the wall thickness is down to .006, but to me it does not matter. For a reference I think your coke can is .0035-.0045”. .006 I expect you could dent with your thumbnail. If a dealer would never submit a gun for proof is it even a gun you ought to buy it and no dealer or smith would e er submit such a thin barrel for proof.

So when you read in the description that “wall below recommended thickness” you need to become very cautious. They are pointing out a potential major flaw and you need to understand it. Many of these guns end up on SealedBid because they are cripples or project guns needing work. In the main sale they list bore measurements for all the guns. They do not do so for sealed bid guns.

KY Jon #616895 07/20/22 12:55 PM
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Are you sure it is .006? That sounds like a misprint. I wonder when the gun was proofed (proved) because at .006 it should be out of proof.

Ken

KDGJ #616896 07/20/22 02:27 PM
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Originally Posted by KDGJ
Are you sure it is .006? That sounds like a misprint. I wonder when the gun was proofed (proved) because at .006 it should be out of proof.

Ken

Proof is only determined by bore size,not wall thickness .
A barrel as thin as that quoted could be the result of a poorly excecuted dent removal in the past .

1 member likes this: Ted Schefelbein
KY Jon #616897 07/20/22 02:36 PM
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A Coke can is .005 thick.

KY Jon #616898 07/20/22 02:42 PM
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As far as I am aware the British Proof houses do not measure wall thicknesses. They take the view that if the tube does not bulge, rivel or burst when fired with a Proof load it is strong enough.

A weakness of that approach is that whilst a barrel goes out of Proof is the bore is enlarged over 10 thou, it still appears to be in proof if under that bore size even if it is repeatedly and over enthusiastically struck down, polished and re-blacked no matter how close the external diameter is approaching the internal diameter.

Some European Proof Houses stamp the weight of the barrels at Proof, and I believe those barrels will go out of proof if they suffer a certain percentage loss in weight.

2 members like this: mc, Stanton Hillis
KY Jon #616899 07/20/22 03:46 PM
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Proofed, proved or in this case poof. Yes I am sure of the measurement. It also is clearly stated in Holts description. The proof house does not measure wall thickness. As to how thick were the original barrels, nobody knows for certain, but I’ve been told they all started out about .020. I have a LeFever 20 which looks mint condition and it’s barrels are .020. It shows no sign of ever being reamed, honed or restruck. So thin barrels can be anywhere. Again I listed the auction item number 5855C. Look it up.

A gun is out of proof if a plug .010 larger than the plug used to determine bore diameter goes down 9” where the bore is measured. So a gun with a .720 bore is still in proof if a .730 plug will not go the full 9”. It might be .728 or .729 and if the plug won’t go it is still considered in proof. Also any alteration of chambers will put it out of proof. So if the barrels start out at .025 thickness and gets cleaned up to .008 to remove pits it still is in proof. But and this is a big, but the wall thickness may have gone from .025 down to .017. Thin but still in proof. You will see this commonly listed as “barrel below recommend thickness”. It is still in proof and legal to sell. Deciding if you want to shoot it requires you to measure it accurately and then make a judgement. But never assume just because a gun is in proof it is always safe.

1 member likes this: Stanton Hillis
KY Jon #616900 07/20/22 05:05 PM
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Per Vic Venters' book "Gun Craft", quoting former proofmaster Roger Lees, who held that position when the 1954 Rules were adopted, referring to those new rules: "in general it may be said that under the new Rules of Proof no arm will receive a more severe proof than hitherto. Some such as the 12 bore 2 inch and 4 and 8 bore guns, will now receive a less severe proof than they received heretofore." I thought I recalled that the Brits went to a less severe proof for the 2" 12, as requested by makers of those guns, under the 1954 rules of proof. I think that continues to the present.

Confusion here, where 2" 12s are concerned, may stem from the fact that when the Spanish made their 2" 12s, they submitted them for 850 bar proof, just like standard 2 1/2" 12s. Which explains why Brit 2" 12s are typically quite a bit lighter than Spanish 2" 12s.

KY Jon #616901 07/20/22 05:33 PM
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Well this is confusing. As Larry said, the data I have is that 50mm have the same pressure standards as 65 mm & 70mm

90 BAR is only 1,305 psi; 117 BAR proof is 1,697 psi
SAPL
https://www-boutique--sd--equipemen...r_tl=en&_x_tr_hl=en&_x_tr_pto=sc

[Linked Image from photos.smugmug.com]

but https://bobp.cip-bobp.org/en/tdcc_public?page=1&cartridge_type_id=7 doesn't show a 50mm standard??

[Linked Image from photos.smugmug.com]

KY Jon #616903 07/20/22 07:58 PM
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I owned a 2” several years ago. The loads it used generated a lot more than 1,305psi. More along 8,400psi. One factory shell I could get were Lavale I think and they were really unpleasant to shoot. About as unpleasant as shooting a 3” 20. 2” 12 were struck light to really be a 20 gauge type feeling gun. You ended up with a 5 pound gun with IM chokes in both barrels. I tried a 15/16 load which patterned very poorly. My best load was a 7/8 ounce load and one Federal paper cutdown load which was 13/16 ounce.

I moved on from it because it did nothing a good 20 could not do much better and the 20 could handle a full ounce where the 2” 12 could not. Or at least mine patterned poorly with anything above 7/8 ounce. I was told one maker made just about all the 2” guns no matter what was engraved on them. For those who own and love them you don’t have to worry about my bidding against you for one. Enjoy them in peace.

1 member likes this: Stanton Hillis
KY Jon #616907 07/20/22 09:52 PM
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An English gun that has passed proof, and maintains the original bore dimensions, but, is down to .006 on wall thickness at some point, has suffered some sort of poor gunsmithing, and, I think this is important, would certainly not pass proof today. Being in proof is just part of the puzzle, other facts and measurements will be required to know what level of ammunition, and, use will be acceptable. The use part is important as well, I owned a very old MacNaughton boxlock, the second gun produced by the firm with steel barrels, that I thought was going to be my daily shooter, clays, birds, Grouse, pheasant, woodcock, everything.

The gun had other ideas. Expensive ones.

Proof is no more than a snapshot of what things were in the past. Compromise is often part of the picture with an old gun. And a gun with .006 wall, is compromised.

Best,
Ted

1 member likes this: eeb
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