doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Safe to lengthen Chamber of 2 1/2" English SXS

Thanks very much to all .
Very good information.
Pete

Alder Adder, so your opinion is that all guns proofed to withstand service loads around 8500psi are safe to fire with cheap SAAMI spec ammo with average service pressures of 11,500psi; and with some allowed to spike as high as 14,000psi, just so long as they feel like less recoil on your highly calibrated shoulder? Have I restated your statement correctly?

Aa - it is unlikely that a SAAMI load is going make an old gun disappear in puff of smoke; barrel burst or bulge is not generally the issue. What is much more likely is that repeated exposure to high peak pressures will "pound" the action off-face and, possibly, loosen it laterally. The metal parts are basically sensitive to high pressure; dram equivalent tells you nothing about pressure. On the other hand, you are correct in that the wood is sensitive to recoil. Keeping recoil down via light shot charges and low velocity is good for the gun and for the shooter. And, frankly, gives away very little performance.

Related question, sort of OT: When foreign makers simultaneously make or made 2-1/2 and 2-3/4 inch chambered guns, was there/is there any difference other than the chamber lengths? I am really thinking of high quality pre-war German guns,some of which were 2-1/2 and some of which are 2-3/4. With all their fasteners and bolting etc. these German guns seem strong enough to withstand about anything, but the same goes for English makers who made both chamber lengths at the same time (and particularly after WW II). It seems kind of hard to believe that they would go to the expense of making two totally different types of guns. I am not talking about pigeon or waterfowling guns that are obviously of hardier construction.

HOS, can't speak for German guns but British guns with 2 3/4 inch chambers were proofed at only a slightly higher pressure than 2 1/2 inch guns. Still way below SAAMI specs. Thus just because a British gun has 2 3/4 inch chambers does not make it suitable for American 2 3/4 inch shells. A British gun must have the "magnum" or 1200 bar proof before it is suitable for US loads.

Regards - Ian Forrester

SXS

I have had a couple of 2-1/2 English and Scottish 16 gauge guns. I opened the chambers on one of them, and now know that was a mistake. My current 2-1/2" 16 is a lightweight Harkom, and I load low pressure 2-3/4" 1 oz. 16 bore loads - under 7000 PSI. They work just fine, and anything heavier would be painful in a 5-1/2 lb. gun.

I have also used the Polywad Vintagers, but they are limited to 7/8 oz. of shot, enough for most of my shooting, but not all.

Reaming chambers on British proofed 2-1/2" guns used to be common practice in the US, but is not considered correct now. The gun will be out of proof, and many smiths will advise against it. There is also the issue of removing metal forward of the original chambers and being left with less margin of safety.

sxsman1, Cabela's sells Gamebore Shells, made in England. 2 1/2" 20 ga., and 2 1/2" 16 ga. and 2 1/2" 12 ga. (65 MM). The price is $8.99 a box. Most have 28 grams of shot (1 oz) and are lower pressure. They used a fibre wad.
There is also a few sites you can go on, and find reloading data for 2 1/2" shells. You can also take 2 3/4" shells and cut them to the right size to make 2 1/2" shells. For 16 ga. go to http://www.16ga.com . If you ask I'm sure someone will give you reloading advise, that is if you reload.
There are some loads there as low as 4400 PSI, and 1100 fps.
I wouldn't go any higher than 7800 psi in your gun.
Also I definitely would not alter the chamber of your gun, as some have stated it was not made for modern loads. David

I was by WilliamLarkinMoore this am and they have several cases of British 2 1/2" 12g 1 oz shells on sale for $5/box. I saw some 8s, 7 1/2s, and 6s. They were fairly hot at (if I recall correctly) 1300 fps.
http://www.williamlarkinmoore.com/index1.html

Ian Forrester: Thanks for your response, but here is my follow-up question re British guns originally chambered for 2 3/4 inch shells. Maybe the makers never asked that they be proofed as "magnums." Case in point, I bought from Christies last year a pigeon gun manufactured by an esteemed Italian maker in the mid 1960s. For some reason, there were no Italian or any other proof marks on the gun. Accordingly, Christies (or the owner more likely) had to have it proofed before they could sell it. The marks read 12/70 900 BAR, although I have no doubt that this gun can and has digested (and was made to digest)hot pigeon loads. So maybe when Purdey or whoever built a 2-3/4 inch chambered gun,they didn't bother to get it proofed for "magnum" (US) shells since it was not necessary to sell or export it; however, that does not necessarily mean that the gun would not or could not have been so proofed.

English guns were made to digest a specified load, no more weight and strength than necessary was build into the gun. It was a finely tuned precision instrument designed for a specified purpose.

Modern guns are build to take whatever ammo they may encounter - hence the 3" magnum steel shot proof applied to Beretta 687 20-bores: even though most will be used for game shooting with a 2 3/4" 23g or 25g lead loaded shell for game shooting.

I get(unreasonably) distressed when I hear of the butchery of the finest guns that Britain produced by foreign owners who do not understand them and the principles on which they were made.

If a British gun is intended to fire 3" shells, it will have 3" chambers, if intended for 2 3/4" shells, it will have those chambers, if it is made with 2 1/2" chambers- use the right ammo or change the gun for something that is intended to shoot your magnum loads.