doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Barrel wall thickness

I'm not looking for a definitive answer here just an opinion. I have a 1920's vintage 10ga Parker with Parker Steel Barrels. The chambers have been lengthened to 3.5". The minimum barrel wall thickness at 3.5" from the receiver is about 0.105. Two questions:
1) Does this fall within the range of safe to shoot? (I have a VHE 12 that measures less at the end of the chambers and I shoot it all the time).
2) Is there anyone who will actually "proof" a gun or at least shoot it a few times in a safe environment of some sort?

I am happy with 0.100 at the end of the chambers in my Damascus guns. I wouldn't shoot modern magnum loads through them however. I certainly wouldn't shoot 3-1/2" mag 10 loads in a a gun that wasn't designed for them.

If I wanted to proof a gun I would find a cartridge recipe that gave me half again the pressure over the regular cartridges I planned to use in the gun. I would handload that load. I would get a table I could sacrifice and some sandbags to hold the gun in place. After I had the gun bagged down on top of the table I would run a string back behind a wall or vehicle and fire the gun from there.

Sending the gun to England to have it proofed is an option too.

Best,

Mike

CP - I'd suggest you have one of the good double gun mechanics/smiths/makers vet your gun. Personally, I don't get the warm and fuzzies with guns that have had the chambers lengthened, especially for magnum loads. Long chambers do not make an old gun suitable for modern higher pressure loads for which it was not designed. The good news is that the action is more likely to be knocked off-face from excessive pressure or the stock crack from excessive recoil rather than the barrels burst.

With due respect to AM, I'm not a fan of do-it-yourself proof. The value in proof is skill in pre and post firing viewing to determine that no metal was permanently deformed. Unless this is accurately done, you run the risk of having damaged the gun during your high pressure firing and not know it.

According to SAAMI standards, the 3 1/2" 10 has a service pressure of 11,000 psi. From some old information I have, back when the 10 was still 2 7/8" (when your Parker was made), proof pressure was 16,000 psi. Thus it would seem you have a reasonable cushion. However, as recommended above, I'd have someone who knows his stuff check it out. Your chambers have been lengthened 5/8", which is quite a bit.

It may be that the barrels would stand proof; but what of the action? I had this raised recently when I submitted a damascus barrel 20 bore to the Birmingham Proof House for re-proof to nitro. The barrel borer was quite happy that there was sufficient metal in the barrel walls. There was, but the action bent like a banana! Lagopus.....

The #3 frame Parker action shouldn't be any problem. Remington routinely rebarrelled Damascus era actions with 3 1/2" chamber ten gauge barrel sets. Frank Lefever and Son sleeved the same old actions for 3 1/2" ten gauge shells. I measured my Lefever-Parker ten gauge magnum and it measures about .100 at the 3 1/2" mark. I also measured a lightweight Damascus Parker ten and it measures about .100 at the 2 7/8" mark. If we were to measure a factory 3 1/2" chamber Remington gun, I would bet that the measurement wouldn't be far from .100. I would be shooting your gun with 3 1/2" shells without much worry. Compare the outside diameter of the barrel at 2 7/8" and 3 1/2" from the breech to get an idea how much wall thickness was given up when the gun was rechambered. I'm guessing it isn't much.

I measured a set of 2 7/8" chamber factory original Titanic Steel barrels and they are .120 at the 2 7/8" mark and .130 at the 3 1/2" mark (gets thicker in the forcing cone area). Apparently, your chamber front end was carved out about .030 to get down to your measurement of .100. Hopefully, they get thicker again when the forcing cone taper takes over. Measuring the outside diameter as I suggested in the last post is impossible because of the water table. Too bad. However, I'm shooting the heck out of my Lefever-Parker with the .100 wall thickness and I've never heard of a Lefever sleeve job blowing up. My gun was probably sleeved nearly fifty years ago and has been used regularly ever since. I'm sure this is more than you ever wanted to know.

It would SEEM that the barrels might be OK in the chamber area after the lengthening (for low pressure loads) but you really need to measure the entire barrels for wall thickness and really check them out for integrity. That is a job for someone really familiar with nice old guns; it is not a casual assessment. And just to shoot it (hoping it doesn't blow) may not be enough to tell you much.

I measured the walls 3 & 1/2" from the breech end on my 10 ga. (1881)it measures .160....it was reproofed after 1950 it's marked Nitro, 4 tons, 1 & 1/2 oz, 3 & 1/2".
It might not hurt it but I don't shoot 10 guage factory ammo out of it.

What make is your 1881 gun?