The CIP site states the numbers are transducer measured BAR simply converted to psi

The Commission Internationale Permanente pour l'Epreuve des Armes Feu Portatives
Infro here
http://www.cip-bobp.org/homologation/en/tdcc_public?page=1&cartridge_type_id=7
12g 65mm and 70mm standard proof lead or steel (limited to no larger than 3.25 mm and max. fps 1,300)
SERVICE pressure 740 BAR = 10,733 psi; PROOF 930 BAR = 13,489 psi
Both 65 and 70 mm 16g standard is SERVICE 780 BAR or 11,313 psi; PROOF 980 BAR or 14,214 psi.
Both 65 and 70 mm 20g standard is SERVICE 830 BAR or 12,038 psi; PROOF 1040 BAR or 15,084 psi.


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