This is an updated version of the CIP regulations converting BAR to PSI using piezo transducer derived numbers
12g 50mm, 65mm, and 70mm “Standard Proof” lead or steel Maximum Average (SERVICE) Pressure 740 BAR = 10,733 psi; Maximum Statistical Individual Pressure 850 BAR = 12,328 psi; Mean PROOF Pressure 930 BAR = 13,489 psi
Both 65 and 70 mm 16g standard is SERVICE 780 BAR or 11,313 psi; Maximum Statistical Individual Pressure 900 BAR or 13,053 psi; PROOF 980 BAR or 14,214 psi.
Both 65 and 70 mm 20g standard is SERVICE 830 BAR or 12,038 psi; MSIP 950 BAR or 13,779 psi; PROOF 1040 BAR or 15,084 psi.
Very good info, Doc Drew.
Of course neither the proof nor service pressure figures are currently stamped on British shotguns. They've been replaced by STD for standard proof and SUP for superior or magnum proof.
