madsenshooter wrote on Jul 9^th, 2018 at 4:04pm:

Interesting to note that he was talking about pressure, without the then normal CUP.  Johan, of Western Powders, told me the limit for Krag loads, expressed as PSI would be around 47,000.

In 1922, piezo transducer pressure measurement had not been developed. Measurements were made by the "crusher" system -  copper for higher pressure, lead for the lower ranges. All results were commonly expressed as "pounds per square inch" (p.s.i.).

After WWII, piezo systems were gradually perfected and adopted by most labs and standards organizations. Since piezo results were expressed as "p.s.i." the C.U.P. (Copper Units of Pressure) and L.U.P. (Lead . . .) terms were developed and applied to results from crusher systems.  This became a source of confusion to amateur enthusiasts unaware of the change in systems and results.

The table pictured below is from a Hercules load data pamphlet dated 1987. Note that some older cartridges do not have established "p.s.i." standards. (SAAMI still has no piezo standard for the .30/40.) Also note how the relationship between the results is neither linear nor consistent - cartridge pressure, shape, and volume all add unpredictable variation.

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