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gspowner
PostPosted: Sat Aug 12, 2006 7:16 pm  Reply with quote



Joined: 28 Nov 2005
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Location: Bend, OR

I am looking at older English sxs 16's and find that they often are nitro proofed for 2-1/2-3 tons/sqin or 5-6000psi. I am a member of the 16ga LPG and don't find much in that realm in the way of reloading data and nothing in the way of factory loads. For example, two factory loads that the LPG had tested are the 2-1/2in 7/8oz Polywad vintager at 9933 Psi and 2-1/2in 1oz RST vintager at 8540 Psi. The lowest pressure factory loads tested were at 7500 and 7720 psi and who knows if every lot is the same.

Anybody out there have experience with this problem? Assuming that the gun is in-proof, do you just use the lowest pressure loads you can find and not sweat the actual proof pressure?

Thanks,

Jim
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Dave Miles
PostPosted: Sun Aug 13, 2006 4:09 am  Reply with quote
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I'm no expert on English proof marks, but I think a 3 ton proof is more than 6000 PSI. Others know the answer for sure.

I found this from another site :
3 tons by British standards are "Long Tons" & are crusher measurements. This should be just under 9,000 psi measured by the piezo electric process.

I'll stand corrected if it's wrong. Wink
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Foursquare
PostPosted: Sun Aug 13, 2006 7:38 am  Reply with quote
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British ton of pressure = 2240 psi. So a 3 ton proof comes in at 6720.

I asked a similar question in the General Discussion forum titled "Proof in the pudding......". Have yet to get an answer.

Pete

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Dave Miles
PostPosted: Sun Aug 13, 2006 10:37 am  Reply with quote
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Okay guys, I might be a little slow here. But isn't 6700 PSI a little low for a 16 gauge proof pressure. The barrels on this thing must be paper thin.
I've got a couple 16 gauge Parkers, on 0 frames, Damascus barrels, and my reloads are between 7000 & 8000 PSI. And I wouldn't be worried about pushing them to the 8500 PSI range. I could see a 2" 12 gauge English game gun being proofed at 6700 PSI.
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Square Load
PostPosted: Mon Aug 14, 2006 11:11 pm  Reply with quote
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gspowner,

The topic of proof tons is currently being discussed on the LPG forum.

Dennis
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Larry Brown
PostPosted: Wed Aug 16, 2006 1:56 pm  Reply with quote
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The tons proof is a unit of pressure, not weight. It's unfortunate that the Brits used the "tons" markings for quite some time, because that confuses a lot of people. There is no direct conversion from tons proof to psi, but basically, if you stay under 9,000 psi with a 3-ton gun, you're safe. This is one we've discussed numerous times over on gunshop, but it pops up at least a couple times a year.
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Dave Miles
PostPosted: Thu Aug 17, 2006 6:42 am  Reply with quote
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if you stay under 9,000 psi with a 3-ton gun, you're safe.
That sounds allot better than 6700 PSI. Smile
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Square Load
PostPosted: Thu Aug 17, 2006 1:40 pm  Reply with quote
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The discussion on this topic on the LPG forum states that 1 proof ton equals 2700-2800 LUP's. So a 3 ton gun would equal 8100-8400 LUP's which would convert ROUGHLY to 9100-9400 psi. PSI can be anywhere from 500-1500 higher than LUP but is usually about 1000 higher. Proof tons were determined by the same basic lead crusher method as LUP's. It appears they used a different unit of measure. It is also stated that test loads were sent to Tom Armbrust by someone (no name mentioned) which confirmed this.

I do want every one to know that I am repeating internet information here.

Dennis
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carpe dm
PostPosted: Fri Aug 18, 2006 4:35 pm  Reply with quote
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I have a couple that say 3 tons, and I just bought a nice English 16 that only says "Proof 1 oz Max." The "oz" proof seems to be common, but I would rather have some idea of pressure, personally. Rolling Eyes

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Chukarman
PostPosted: Thu Aug 24, 2006 8:42 am  Reply with quote



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One ounce proff is approximately equivelent to 3 tons proof.

I have a 2-1/2" Brit 16 proofed 3 tons. I shoot a 1 ounce load that is rated at 8400 PSI. I also have other 1 oz. 16 gauge loads rated as low as 7000PSI.

If you would like the loading spread sheet with over 900 loads, PM me with your e-mail address and I will send it along - no charge.

C Man

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Larry Brown
PostPosted: Thu Aug 24, 2006 9:14 am  Reply with quote
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Carpe, your gun with the "max" proofmark was made between 1896-1904. Generally speaking, steel was not as good in the pre-WWI guns as in those made after the war, due to advances in metallurgy. With that gun, I'd be especially careful with pressure. As C-man said, there are some 7000 psi formulas out there, if you reload. The 1 oz thing made sense--in England, back when that gun was made--because all 1 oz loads were essentially the same in terms of pressure. That, of course, is no longer true.
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carpe dm
PostPosted: Thu Aug 24, 2006 11:08 am  Reply with quote
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Larry: Thank you for the explanation of the "max" proof mark. I thought it must be something like that. I am sticking to 7000 or less. Wink

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