16ga.com ~ View topic

*Last edited by revdocdrew on Sat Dec 30, 2006 1:27 pm; edited 3 times in total*

1 psi = .06895 bar
1 bar = 14.50377 psi

600 bar = 8,706 psi
650 bar = 9,432 psi
700 bar = 10,157 psi
800 bar = 11,608 psi
850 bar = 3 tons = 12,328 psi

**650 bars is standard CIP (British and European) pressure for shells designed for guns proofed at the CIP standard of 850 bars**
Per Larry Brown: "Per the master of the Birmingham Proofhouse, the problem with any psi/BAR conversion is that BAR still means crusher BAR, not Piezo BAR, to the Brits. Proof pressure is 13,920 psi; service pressure 10,730 psi. This is very close to equivalent to American standards before modern, 2 3/4" shells were introduced in the 1920's."
Information about proof: http://www.basc.org.uk/media/100_proof.pdf

Conversion table http://www.unitconversion.org/unit_converter/pressure-ex.html

Member Joined: 08 Nov 2005 Posts: 3438 Location: Illinois

Thanks----I was looking for that conversion the other day Cool

Member Joined: 26 Apr 2005 Posts: 743

You've got to be careful when converting bars to psi and vice versa. You first need to make sure you're talking apples to apples--that is, you need to be converting pressure measured via the same means. For example, although 650 bar converts to less than 9,500 psi using the formula, and although 650 bar is standard service pressure on an 850 bar proof British gun . . . that ain't the right answer. Birmingham Proof House set me straight on that one. They still use the old lead crusher method of measuring pressure. Remember LUP, or lead units of pressure, in older reloading books? That's what we're talking about. And for a ballpark conversion, LUP to psi, you add 1,000 to the LUP figure. So that 650 bar service pressure isn't 9,500 psi. It's 9,500 LUP, because of the different measuring system. That means you ballpark it by adding 1,000, comes out to 10,500 psi--although it's actually about 10,700 psi, per the Birmingham Proof House.

I believe you Larry, and looked for a LONG time, unsuccessfully, for something actually documented in print. Do you have a reference?

Member Joined: 04 May 2005 Posts: 123 Location: Oregon

Drew, Larry's reference is the Birmingham Proof House. I finally found where I stored Larry's original post concerning this. This is what he had to say back in March of 2005: "Per the master of the Birmingham Proofhouse, the problem with any psi/BAR conversion is that BAR still means crusher BAR, not Piezo BAR, to the Brits. So in fact, both proof and service pressure for standard 850 BAR guns are a good bit higher than many of us (myself included) had previously thought. Straight from the Proofhouse: Proof pressure is 13,920 psi; service pressure 10,730 psi. This is very close to equivalent to American standards before modern, 2 3/4" shells were introduced in the 1920's. In other words, any loads that will work in 850 BAR British (or other CIP) guns should be fine in your older Elsie, Parker, Ithaca etc."

Of course all of that means providing you have had the gun checked for barrrel wall thickness to make sure that somewhere down the line someone didn't do some serious honing to rid it of pits or that someone didn't get carried away prepping the barrels to be reblued. I have such a gun. Both barrels measure at least .085 all the way around right in front of the forcing cones except for one spot on the outside of the left barrel and it measures .073.

This means that Eleyman's 720 Bar average figure comes out closer to 11500 psi which is way under the 850 Bar PROOF pressure but way over the SERVICE pressure which he was confusing with PROOF pressure. So if those Eley shells really are CIP rated shells then he has to be wrong about the 720 Bar pressure figure he gave me.

Why am I not surprised? You have to be really careful when the health of your fingers are concerned because the internet abounds with misinformation.

Thanks to Larry for setting us on the right course.

Larry

Thanks for finding that Larry and BTW: I just got back from Ben Avery's pattern board (sorry Josh!) Excellent bird whacking patterns with the Eley shells at 25 yds through my .007 and .014 brls and slightly less recoil than the Gamebore 1 oz. at 1260, so I'm confident those shells are indeed the 1225 and not the 1380 load. Patterned much tighter than the Gamebore 7s also. Through the .014 brl, had >90% of the shot in a 20" circle at 25 yds Very Happy

Member Joined: 04 May 2005 Posts: 123 Location: Oregon

Thanks for the information Drew. I haven't got my Eley shells yet but they are on the way.

Have you tried the new Poly-Wad 7/8 oz. XXtra buffered loads yet? They sound kind of funny (low noise, almost hollow) and blow some confetti out the barrel due to the craft paper wad but they are extremely low recoil. So much so that I tried to clock them on my Chrony just to be sure they could kill something but couldn't get a consistent accurate reading due to the confetti I think. Jay assured me they would kill birds so I tried them on wild chukars and managed to kill some stone dead at 30 yards with a .010 choke. They patterened 90% (180 evenly distributed pellets, no hot center, inside the 30" circle) at 40 yards with a full choke barrel but still gave good 28" coverage at 20 yards out of a cylinder choke.

Larry

Joined: 19 Jun 2004 Posts: 1480 Location: Mpls, MN.

Which Eley shells? I have been using the fibre wad VIPs with stellar results.
Best,
Ted

Member Joined: 04 May 2005 Posts: 123 Location: Oregon

Ted, we're talking about the Eley 16 gauge Grand Prix that August offered for sale here: www.eleyshotshells.com He also had some VIP's but I think he may have already sold out and isn't offering any more in the future.

Larry

Member Joined: 26 Apr 2005 Posts: 743

Drew, IFL16 saved me the trouble. The quote he posted from me is straight from an email from the Birmingham Proof House. I received it back when I was preparing an article on chamber length, proof, etc, for Shooting Sportsman. Glad I did too, because just like almost everyone else (and we'd pretty well reached agreement over on doublegunsho as well on the subject), I thought standard Brit/European service pressure was in the 94-9500 psi range. Not that it isn't always a good idea to err on the safe side, but nice to know there's somewhat more leeway with guns with the modern 850 bar CIP proof--although they still aren't up to SAAMI service pressure standards.

Eleys . . . I was shooting Grand Prix 30 gram Brit 6's at pheasants this year (2 1/2" 12) until I ran out, at which point I switched to the same load, Gamebore Pure Gold. Both have worked very well for me.

Larry Brown,

Is that the article you wrote for the Jan/Feb 2002 issue?

Dennis

Found this in my 'gun stuff' file but unfortunately, did not document the source:

"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."

Once again, per Larry's correspondence with the Birmingham Proof House, we're apparently talking different LUPs.
Why is this so hard and why don't ammo makers document speed and pressure data? You'd think it would actually protect them rather than increase legal exposure Mad

And from "Story Of European Proof Marks" by Englehardt Part II, Chapter II Proof In France.

"St. Etienne Proof Loads between 1885 and 1923 (Chart inserted in the text) shows the Proof of finished barrel produced 893 Kg/sq CM. The extra strong proof was 1050 Kg/sq CM, Double Proof was 1472 Kg/sq CM, and the Triple was 1800 Kg/sq CM. The same chart also shows the normal load of 16ga shotgun cartridge in France during that time was 438 Kg/sq CM."
And "...the 438 Kg/sq CM service loads might give us a reasonable response of approx 6230 psi. There will be problems in the conversion as we don't know exactly how these pressures were measured but quite probably by LUP so we can add about a 1800 psi to that for stress gage pressure reading equivalents. So an old 16ga prior to 1924 was probably intended to handle around 8000 psi as measured by strain gauge."

Member Joined: 26 Apr 2005 Posts: 743

Square load--that is the article I referred to.

Drew, you're finding velocity marked on more and more American shotshell boxes these days. Why don't they mark pressure? Because they load with bulk powder, and as long as they stay within SAAMI service pressure standards, they don't care what the pressure is. Might vary from lot to lot, should they change bulk powder. But I know they test for pressure. I've visited the Federal factory and saw their pressure gun setup. They're not concerned with pressure, as long as it's within SAAMI standards. They're looking for consistency in velocity (especially in target loads), shells that will cycle autoloaders, stuff like that.

Per the British example . . . I think that's exactly the way most people arrived at 94-9500 psi as being standard service pressure for Brit/CIP guns. However . . . the "tons" marking on Brit guns is now about 20 years out of date. I'm not sure where the 1 ton=27-2800 LUP thing came from. However, on a box of Brit shells I have, it says: "Suitable for use in . . . guns with a chamber length of 2 1/2" or longer, nitro proofed to a service pressure of 3 tons per square inch (850 kg per square cm)." That would seem to indicate that 3 tons=850 bars. However, we know that 850 bars is not service pressure, but rather proof pressure--so I'm not positive the two measurements are in fact equal. All I'm sure of is that the shells in question are fine in a gun marked EITHER 3 tons or 850 bars.

I would like to know the age and what my maximum pressures should be.
Can you tell that from the Proof Marks? I will try to include some pictures. http://www.flickr.com/photos/delco1/956926129/
the pictures are tagged with "16ga"

delco: The Savage model 220 single barrel was made from 1938 through 1965. US gun makers 'prooved' their barrels independently using over-pressure loads. If the gun is in good working order and the barrel is free of pitting or previous honing, it would be appropriate to use 1 oz 2 1/2 dram (1165 fps) 'Game Loads.'