doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Pressure vs. Velocity

JMHO, but I can't see a valid reason for anything over 7 or 8000psi in the 12ga. If you want clean barrels and action, then yes. But most of us here talk SxS's, and many of us old SxS's, and some of us with Damascus barrel SxS's. I don't mind a little unburnt powder in the barrel. In the warmer months my reloads are under 7000psi, and in the winter when it gets below 15 degrees or so I up it to around 8000psi. Paul Harm

Paul,
No wonder I'm out of the loop on this cold weather thing. Houston thermometers implode at 32F.

Bill

A few comments on the last couple pages:

1. If you have a British double proofed under the old "tons" system, that figure (which you cannot convert to psi via multiplication x 2,000, nor even 2,200 for a Brit "long ton") is SERVICE pressure, not proof pressure. It wasn't until they changed to the "bars" proofmarks that you got a representation of proof pressure.

2. If you're reloading, you want to focus on SERVICE pressure, which is significantly lower than proof pressure. The reason we have proof is to test guns at much higher pressures than they'll be subjected to via hundreds or thousands of rounds. You can look at the difference between proof and service pressure as a safety cushion. But the best idea is to stay under the SERVICE pressure for the gun in question. If you're feeling gutsy and think it's OK to flirt with PROOF pressure in your reloads, it's good to remember that Winchester did exactly that, with all the American doubles of the period, after their Model 21 came out. And while all the American doubles did survive at least several dozen proof rounds, they all eventually failed--which is no big surprise, because those loads aren't meant for repeated use. They'd kick the snot out of you, and very likely crack the stock before they did anything to the barrels. The Model 21 was the sole survivor of that torture test, after something like 2,000 proof loads.

3. Depending on the gun for which you're reloading, going up to 10,000 psi in the 12ga can be unwise, IMO. The current CIP service pressure for "standard proof" 12's (those marked 850 bars) is 10,730 psi. If you're doing what many of us do, and reloading 2 3/4" hulls and shooting them in guns with 2 1/2" chambers, a 10,000 psi reload per the published recipe can easily exceed 11,000 psi because of the extra hull length. It's safe enough to reload 2 3/4" hulls for 2 1/2" guns, but in that case you need to build in an extra safety cushion if you want to make sure you stay below the established service pressure for the gun in question.

Like Mike Campbell, I've always been either Larry Brown or L. Brown. I post more after the basketball season is over, when I'm not busy coaching. I have no experience in machining, nor chemistry, nor anything of that nature. I do have a fair amount of experience with vintage guns, both American and foreign. I've written a bunch of articles about them, and I've worked for some pretty sharp editors who've saved me from a few mistakes. When I write about subjects such as proof, I try to be very thorough in my research. I don't rely just on my own experience, which also includes tens of thousands of rounds (mostly reloads) through vintage doubles. All of that is still anecdotal. I try to go to reliable published sources (like the Birmingham Proofhouse, in the case of British guns) as well as information dating from the time when our vintage American doubles were still being produced. Because I do write for publication as well as on various BB's, I always try to give advice that will keep readers on the safe side. If others want to experiment with loads that exceed the service pressure for a particular gun, that's up to them. But I won't recommend it.

Am I losing it, or didn't someone ask for Ithaca Flues recommended loads?!?!

1917 "Bored for black or nitro powder"



c. 1910 Flues era Ithaca Gun Co. 12g �Lightning Lock� hang tags state the guns were patterned with No. 8 chilled shot in a 24� circle at 35 yds using 3 Dram �New Schultze� Smokeless powder and 1 1/8 oz. shot.
Pressure by modern piezo transducers would be less than 8000 psi.

More infro here
https://docs.google.com/a/damascusknowle...fUOZEFU/preview

Drew,
Thanks for the post. Hopefully Tom C is still checking the thread. Per our previous discussions, yours was one of the sources that led me to the 8k max number. I feel using the 8k max for small bore is a safe bet as well.

Best,
Bill

Larry, it puzzles me that you and others so actively promote the practice of loading 2.75" shells and guesstimating pressures in 2.5" guns....ESPECIALLY the very people who are so concerned about pressure in the first place.

If you want to keep readers on the safe side, maybe you should advise them to use published data expressly for loading 2.5" shells. If people don't want to use that, they can simply pick any 2.75" recipe at any pressure level they like, trim 1/4" off the hull and either roll-crimp or use a Hartin crimp. Pressures changes will be virtually statistically insignificant.

Makes me wonder, what fudge factor should I use for loading 3" shells for 2.5" guns? Or has that article not been published yet?

Yours in candor, Mike

I'm not that interested in this thread, but I seem to recall some articles published by the load testing guy addressing exactly the long shell in a short chamber pressure question.

Drew- OP said NID in good condition.

With regards Ithaca Flues models and higher pressure shells, dumb idea. Not that the barrels will blow, but that you'll break the corners off the top of the stock.
I have 6 here right now with broken top corners. It's a design issue. No way to draw the stock into the action. When the wood shrinks a little, it gets pounded to pieces. Well, actually fractured off.
So, while they may not blow, the bolting gets all sticky, and the stocks break. YMMV.

CZ,
Never cracked a stock but had a 12ga Flues double when I was a kid (71-72) and crack the water table in the thin area on the right side. Still have the gun. Smith welded the action and its still running like the Eveready bunny with 1oz LP loads. Love the old Flues guns. Have 4 right now, one 12ga, two 16's and a 20ga. I think this sums it up real well

"With regards Ithaca Flues models and higher pressure shells, dumb idea."

I suppose there is no real answer to the question.
As long as they can be transferred freely, vintage doubles will end up with high pressure cartridges stuck in them.
I'm only breaking targets with them most of the time anyway. I don't need the heavy artillery to do that. Broke two stocks on the same day shooting Estate 1.125oz shells. One a Flues, the other a Nitro Special. YMMV

It wasn't higher pressures in the Estate shells that broke them, even tho' their pressures probably were in the 9-10K range. It was the combination of velocity and payload, generating too much recoil for the old wood, or poorly inletted old wood. I can load shells that will generate the same recoil as that Estate shell, without high pressures, and wreck one old gun after another with them. JMEO

SRH