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Old November 29, 2019, 05:05 PM   #6
Join Date: March 4, 2005
Location: Ohio
Posts: 18,701
Not too surprisingly, the number is close to the 56,000 psi established for the 284 Winchester, which has a copper crusher rating of 54,000 CUP. That the difference between the two is is only 3.7% is probably a measuring system artifact. Other cartridges with a copper crusher rating of 54,000 CUP like the 264 Win Mag, have psi ratings above 60,000 psi. The European system seems to be more consistent at capturing absolute pressure differences. The CIP has different ideas, though. They use 4,400 bar (63,817 psi).

That difference of almost 6,000 psi is within the SAAMI MEV (maximum extreme variation) value of 12,000 psi. It is below the SAAMI minimum proof pressure of 74,000 psi. Modern bolt guns should have no issue with the higher CIP number, though if you run into a self-loading or a lever gun chambered for it, I would be inclined to load down to the SAAMI limit.
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