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

As Ed McMahon, would say, "You are correct sir". It is service pressure, not proofed pressure. A fatal error on my part! Especially if you loaded to proof pressure! One thing I do with my hunting loads, I measure each powder drop to make sure the loads are consistent. I use 800-X, which I personally like a lot, no real powder migration, performs well in cold weather etc. But, it's a large flake powder and meters like crap. So, I just weigh each drop, peace of mind and I know I won't go above the published pressure.

Best,

Greg

So I now understand where to be on the low end of pressure but need a little clarification on the high end for the guns I am shooting. I am shooting a Parker Trojan, Sterlingworth and an Ithaca NID all in good condition with good wood. Drew has offered some loads that go as high as 10,000 psi. What's a safe upper end for pressure?

Tom,
You will probably get a number of opinions on this. If you are shooting 12ga, I would stay below 8K. Not because the guns you list couldn't take it, but why subject your babies to the possibility of premature wear. There are MANY loads below 8K. I will leave the "safe" portion of your question for those more knowledgeable than me.

My logic was that 3 tons is approx 8.9k psi. The lowest British proof I have seen is 3 tons. I then rounded down by approx 10 percent.

JMO and will be interested to hear what others think.

Ithaca1

Hi, just my 2c again. I agree with Ithaca. Your guns can more than likely take it as he said. American doubles as a rule have much thicker bbl walls than Brit guns and pressures can be higher in American guns, but why subject your gun to more punishment than needed.

Also, I'd check your chamber lengths, they may have been punched out or they are short chambers to begin with. That can have a bearing also. American guns aren't my forte, so I'm sure someone with much more knowledge will step in.

Good Luck!

Greg

Tom,
I load for 12,16,20,28 and now 410. All of my loads are sub 8K psi except the 28ga. The 28ga is English proofed at 3-1/4 tons, which is about 9.6K psi. My go to load in it is 8.4K. Still falls within my self imposed 10% under service pressure rule. If you need small gage loads to get started PM me.

I would LOVE for someone to offer up a sub 8k handload for the 28ga. in an AA hull.

OK.

I have a gun that I think has a proof pressure of 8938 psi. In that case, I obviously don't want to shoot 9,000 psi shells in it.

But maybe 8938 psi is the service pressure, meaning the gun was deemed to safe to shoot 8,000+ psi loads day in and day out, for tens of thousands of rounds, for years and years without incurring anything more than normal wear. Hmmmm, should I hang my hat on a number like 8938 when actual pressure testing probably can't distinguish 8900 form 9300 with any scientific certainty? Proof pressure or service pressure, does it really matter? What matters is that 7,000 psi is better than 9,000 psi, right?

It also has 2.5" chambers. Maybe I should buy or reload 2.5" shells with recipes suggested at 7,000 psi?
All I need is some published data, a razor blade and a couple of washers and I can be shooting 7,000 psi, 2.5" shells in my frail old Brit gun. Nah, I have a better idea.

I'll just listen to people who "understand vintage guns." I'll load some 2.75 " shells (with some crappy metering powder and a substitute primer) and shoot them in my 2.5" chambered gun where I imagine my pressure will be around 7000 psi.

(I'll have) "peace of mind and I know I won't go above the published pressure."

Now I understand.

Hey, just a FYI, the recipe I use is a published load. The load can be found on the IMR reloading site. If a person can't trust a published load from the powder company, then why bother to reload at all? As to the other statements, well we all have our opinions and different points of view. That's about all I can say.

Best,

Greg

Now that you have written 3 + paragraphs of sarcasm, perhaps you could sum up your plan of infinite wisdom.

As you have said in other condescending posts... "I'm willing to learn", as am I. Perhaps, just a though, you could add something constructive, instead of going through life as a prick.

I've learned a lot on the various boards in the 20 years I've participated...always as Mike Campbell. That's my name and I use it because I've never written anything that I'd be embarrassed or afraid to have associated with my name. In keeping with my persona as a sarcastic prick, I'll sometimes comment on the posts made by the thousands who hide behind phony handles, despite their having the credibility of a 12 year old girl in a party mask.

Well Mikie, my name is Bill Johnson and you still haven't given us the benefit of your wisdom here. Do you have anything of value to add to the thread on pressure? What exactly are your credentials giving you such insight that you feel like you can belittle people? "I'm willing to learn".

I will say, I spent 18 years in NY. Couldn't leave quick enough. One of the main reasons was an overwhelming number of people such as yourself. Happiness was seeing NY in my rear view mirror circa 1977.

Oh, my degree is in physics and I own a machine shop. Somewhat applicable to mechanical things.

You hit the girly party mask on the head. The guys in the shop are always after me to take off.

Bill Johnson
Ithaca1