Okay, I know I'm not alone out there, I have a Spartan 45-70 double that operates under 2200 BAR or 3190 HST... WTF!? I've been trying to find a simple conversion (BAR to CPU) but it seems like no one in this world can agree on how to arrive at such a conversion. I just want to know, not guess at, what CPU level I can reload. HELP

Well a BAR is 14.5PSI so 2200 Bar is 31,900 PSI. Have no clue what aHST is excpet it appears to be equal to 10psi There is no direct conversion from psi to Cup since they are measured differently. Data I have shows the 45-70 as 28,000 for both PSI and CUP. Those would be what the loading manuals would use for the Trapdoor level loads.

Col:

This is easy. The rifle is Russian, and the markings are 2200 BAR/31900 HST - the CIP standard MAP (max average pressure) for the .45/70. 2200BAR X 14.50375 = 31,900 PSI. CIP is the European version of SAAMI. Their methods of testing pressure, either CUP (crusher) or PSI (transducer), are not the same as SAAMI's. Their pressure standard for the .45/70 is the same as ours. The numbers are different because of the different protocols used.

Use American data for the 28,000 CUP/PSI standard and you'll be fine.
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"Serious rifles have two barrels, everything else just burns gunpowder."