doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com proof

I am looking for a correlation between proof and psi for the purpose of finding more powerfull loads that won't spoil my guns. Can anyone point me in the right direction

You may have signed up to the wrong site, Justin, if you are looking for more powerful loads to shoot through older doubles. Most of us here go to some extremes to create and share loads that are just the opposite. Old guns are old guns, and generally should be used only with loads that purposely are created to be lower pressure than the gun's original proofs, in the interest ggenerally of helping some of the really fine old guns make it another two or three generations. Could you tell us what guns you want to use, and for what purposes? That's a beginning point for us to know how to better answer your question. There are no doubt other sites better suited to sharing magnum water fowl type loads, if that is the direction you might seek. Some here no doubt go both ways (I always wondered about a couple guys in particular that might go both ways) If you have a modern thunder stick, that's a different story, and some here can answer better than I for such guns. Proof levels can be determined in some cases, but you certainly don't want to approach proof load levels in any gun, including modern guns. If they don't blow, they surely will wear very quickly.

Justin,

What guns are you talking about? Why do you want hot loads?

Pete

pete,
I'm talking older 12bs, turn of the century
. I'm looking a benchmark to base my loading on. I normally load the lowest psi for the velocity but I want to know more about wht the proof signifies.
Justin

chief,
Thanks for the reply. I am not looking to blow the barrels off my old 12. I just want to be able to understand what the brits mean when the barrel is struck 850bar or 1&1/8 oz in regards to psi. I'm not looking for mag loads I'm just searching for efficiency.
Justin

Justin: this speed/pressure (in both BAR and PSI) chart at least gives an idea of the relationship of BAR to PSI, the shot weight, and speed.
http://www.bandpusa.com/files/db_trio.pdf

Justin:

Welcome to the board. Hope that you will hang around.

As for your question. Please understand that velocity has very little to do with pressure. You can get good velocity with moderstae pressures, if you are judicious in your powder choice.

Just skimming through the Alliant Powder manual, under STS hulls ( which I use exclusively ) I find a load using Unique, that gets a quite respectable 1200 fps out of an 1-1/8 oz that is circa 7300 psi. For a duck load, 1-1/4 oz at 1200 fps can be gotten for 8400 psi with Herco. There are a a goodly number of good payload, good velocity loadings that are in the 7000-8500 psi range. If you use other hulls you can find numerous others.

Guns such as you describe , 2-1/2" 12, were designed for service with loads in the 9000-10,000 psi range. You will find the biggest issue is not the metal, but wood. Wood which has dried out, or has not been properly cared for or has gotten a bit oil soaked, can crack at the head when you subject it to magno-blasters.

Is high velocity worthwhile? I think if you will look at the basic physics here, you will see that the high velocity loads kick a good deal more , but by the time the pellet has reached 40 yards, the difference is inconsequential. The more rapidly projected pellets slow down faster.... drag works like that.


Good Luck

Regards

GKT

Welcome to the site. There are many very knowledgeable people here who are willing to share.

There was a series of articles written about proof marks and the tests that some of them represent. They were written in Gun Digest over a 12 year span. You can pick up individual Gun Digests on eBay for about $5.00 - $10.00 each. Two that may help are:
31st Edition England - 1977
32nd Edition Belgium - 1978

Also the Birmingham Proof House maintains a nice website. They sell a lot of documents that may help answer some of your questions. http://www.gunproof.com/Price_List/price_list.html
They also have CD available with many of the documents from C.I.P.

Safe pressures are easier to determine if you just name the gun, condition, any existing proof marks, chamber lengths, etc.

Most people feel about 5,000 psi is safe for many damascus barrels. But this can vary a great deal. If the gun in question is a British gun in excellent condition with Nitro proof marks in can most likely handle heavier loads versus an unmarked gun with heavy pitting of the bores and a loose hinge which should simply not be shot at all. Because a gun has fluid steel barrels does not mean it can handle modern loads. Manufacturing tolerances have changed along with the steels available to the gun maker. So, as Greg states, a load of 10,000 psi may be safe, again depending on the original gun and it's current condition.

There is no correlation between proof and pressure. It is very direct. The gun is subjected to loads that produce known pressure levels in excess of normal loads. The gun is measured at many points before and after the test. If any changes occur, the gun does not pass. These tests are well documented, including the powder and charge used in each phase of the tests.

There is no proof house in the USA. There are however, proof loads, "blue pills" that are not available to the general public. But this does not apply to guns built 100 years ago.

Please, ask questions before you decide to grab some Wally Save a Buck Loose a Thumb Duck load and fire away.

Pete