doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Kgs. vs. Bar etc.

Per the Birmingham Proof House, 850 bar proof converts to just shy of 14,000 psi (because they still use crusher values). Service pressure for such a gun is 10,730 psi.

The gun is a 1970 Ugartechea 12 ga. with 3" chambers. Sorry, I should have said in the original post.

If you look more closely, I expect that what you will see is that the kg is really kp for kiloponds. A thousand kiloponds is slightly less than a thousand bar.

My Arrietta 601 was proofed in 1982 for 1200 kp which is about 1768.798 Bar.

Spain followed Germany in the use of kiloponds and continued even after Germany switched to kilograms and then to Bar to prevent confusion between weight and pressure.

I think that Spain went to Bar in 1987.

danc

The pic on the 1000 kgs. didn't come out good, but it is kgs.

Here is a 1966 Aya with 900 kgs
http://www.shotgunworld.com/bbs/cpg1410/displayimage.php?pid=7464&fullsize=1
Here is a 1980 Spanish with 900 kp/cm
http://www.shotgunworld.com/bbs/cpg1410/displayimage.php?pid=7463&fullsize=1

So, are they different?

The "Imperial" (Long) ton equals to 2240 lbs. By simple multiplication 3 & 3¼ tons psi would relate to 6720 & 7280 lbs psi rather than 6,000 & 6,250 we would think of using the US 2,000 lb "Short Ton".
Note also these are "Crusher" pressures & should not be confused with actual PSI. Many, Many years ago the British ran some tests with a pressure gun set up to simultaneously record both Crusher & PE (actual psi) pressures from the same shot. A series of these led to the result it was stated that for practicl purposes a formula could be used "Within normal shotgun pressure ranges" of 1.5T - .5tT = psi.
Working through this formula for the 3 & 3¼ ton loads
gives psi readings of 8960 & 9520 respectfully. These PE reading are thus a full Ton (2240lbs) "Higher" than the respective crusher pressures. Also note I have "Nothing" at all to indicate this is applicable to any systems of recording pressures other than the British one with which the tests were run.
Though I have no exact knowledge of the fact, at the time these tests were run they were likely done using a bulk powder such as Schultz or EC. It is entirely possible, even probable, that like tests run with powders of varying burn rates would produce varying results.
In Short, There simply is "NO" reliable method of converting crusher pressures to True PSI. Not this formula, Not adding 1,000 lbs or any other simplistic method.

I have one source that gives essentially the same numbers Miller listed under the previous "tons" markings. But I have another one that states that the "tons" values convert to the current CIP system (bars). In other words, the markings changed, but the proof and service pressures did not. In that case, 3 tons represents the service pressure for a gun with an 850 bar proof, and those numbers--straight from the Birmingham Proof House--are 10,730 psi service pressure, 13,920 psi proof pressure. That would make a 900 bar gun capable of handling the SAAMI standard 12ga pressure of 11,500 psi.

We're still falling a bit short of speaking the same language as our cousins across the Pond.

Hello Patriot

First. I should have written p.s.i. instead of bar.
1200 kp = 1176.798 bar = 17068.014 psi

Second. Germany went to bar to prevent confusion with kg and kp.
Spain switched also but at a later date.

Re pictures. If in 1966 a customer wanted proof in kg, I am sure that a manufacturer would oblige at the customers expense of course.
danc