Here is a question and answer segment from a Field and Stream magazine from June of 1922. The shooting editor is encouraging a subscriber to sporterize a Krag for hunting. An interesting tidbit showing the mindset of the day.

Here is the question:
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Here is the answer:
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My 1896 sporter had the recommended "Sheard Gold Bead Front Sight" in a 1903 base. The front sight base was beat up so I replaced it with another 1903 base and a Marbles bead. Although my barrel is 6" shorter than the issued 30", it is a 1903 barrel from the Rock Island Arsenal.

I agree that reading sporting magazines from this era is quite interesting. Even the advertisements are of interests. In one of them I read an article about the debate of gun control. Instead of 1922 it could have been written today, the same arguments given by both sides are still being used. Below is a link to a series of monthly magazines of Field and Stream from 1922. I'll being check out the American Rifleman mags.
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madsenshooter wrote on Jul 9^th, 2018 at 4:04pm:


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.