Ted: I couldn't find the previous thread discussing the inexplicable failures at the Birmingham Proof House, but this was clarified to mean ONE round that develops the desired pressures at both 1" and 6.38"
2006 British Rules of Proof
http://www.gunproof.com/Proof_Memoranda/RULESOFP.PDFPart IV, “The Proof Load”, Number 27, Part A
Calls for a load of 30% over mean service pressure at a point 17mm or 25mm (about 1”), and at a point 162mm (6.38”) from the breech face a load of 30% over mean service pressure (at that point as determined by the Proof House).
"Mean Service Pressure" is probably 650 bars (9,427 psi) or maybe it is “Maximal Average (Service) Pressure” 740 BAR = 10,733 PSI.
“Mean Proof Pressure” is 930 BAR = 13,488 PSI, or maybe 960 bar = 13,924 psi.
9,427 x 1.3 = 12,255
10,733 x 1.3 = 13,953?What the pressure is suppose to be at 6" is a secret, as is the powder in the proof load, and I've given up
