doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Help needed on pressures of modern loads?

From Larry Brown's recent communication with the Birmingham Proof House, I thought an addendum should be placed at the end of this thread in case anyone is saving it for future reference:

**650 bars is standard CIP (British and European) service pressure for shells designed for guns proofed at the CIP standard of 850 bars**

European (CIP) proof pressure of 850 kg per sq. cm. (BAR) = 13,920 psi proof pressure= 10,730 psi service pressure (SAAMI)

Per the 1954 Rules of Proof, here are the equivalent service pressure values:
3 tons--8,938 psi
3 1/4 tons--9,682 psi
3 1/2 tons--10,427 psi
4 tons--11,917 psi
These numbers SHOULD apply to guns proved under the 1925 rules, which were stamped only with chamber length and shot charge. Thus, a 2 1/2" chambered gun, 1925 rules of proof, would be equivalent to 3 tons; a 2 3/4" chambered gun to 3 1/4 tons.

A service pressure of 3 tons per sq. in. = 8,938 psi service pressure (SAAMI)

Indeed! Thanks Rev Doc.

jack

Went through this thread (for about the 10th time) as Dave may add it to the FAQ Forum and found an error on p. 4

"In 1989, all proof data was marked in metric using the BAR as the unit of measurement. The use of kilograms per square centimetre was dropped. Under this system, 850 bar represented standard proof, with 1200 bar being special or magnum. 2 1/2" chambered guns are usually proofed 850 bar (3 tons per sq. inch)
2 3/4" chambered may be proofed 900 bar (3 1/4 tons per sq. inch) or higher."
This should read:
In 1989, all proof data was marked in metric using the BAR as the unit of measurement. The use of TONS per square inch was dropped. Under this system, 850 bar represented standard proof, with 1200 bar being special or magnum. 2 1/2" chambered guns are usually proofed 850 bar and 2 3/4" chambered may be proofed 900 bar or higher.

I interpret all this to mean that the SAAMI psi conversion for the 1954 TONS measurement is different from the 1989 BAR measurement.

BOTTOM LINE: ANY 850 BAR (proof) = 650 BAR service or 3 TON service gun should be fine at pressures under 8500 psi, or 3 1/4 tons less than 9,500 psi.