This question came up a while back and curiosity got the better of me so I did some digging. If anyone has better or more complete information I would like to learn more about this subject. There was no national German proof law before 1891.

From Baron Engelhardt:


“Rifles using the 8mm cartridge and later on all rifles using similar ammunition with jacketed bullets and smokeless powder were proved, according to a special decree published in the Reichsqesetzblatt (law bulletin for the German Reich) of July 23rd 1893, (227) once only with a special proof load, consisting of a specially strong powder made at Spandau, developing a pressure of 4000 metric At. It was known as 4000 At powder.â€

4000 atmospheres would be 4000 X 14.7 Lbs per sq inch or 58,800 psi.

This would cover the original 8x57-88-I (j) and I can’t find any new law to cover the later 8 x57 -98-“Sâ€. As far as I can tell there was no change until 1939 so if anyone has this info, please share.

IF M98 actions were only proofed at 58,800, that would help to explain why some seem soft when used with high pressure loads.

I believe the "blue pill" load used at Springfield Armory for proofing the '03 Springfield and its successors developed about 25% greater pressure than this. Interesting, if true, that those much-maligned "low number" 1903 actions all stood a proof load greater than the one used for the M98 Mauser.

Different weapon, but about the same time period...US Krags were “proofed†using a cartridge that produced a specified pressure ⅓ over the amount produced by the Frankford Arsenal service round. They shot five of them to proof the rifles.

Brophy discusses this in his book on Krag Rifles.

I do believe that they were proofed closer to 58,000 CUP. In older data it is not uncommon to see CUP units given as psi or PSI. Best-o-Luck

Since we are talking about weapons made in the late 1800’s and pressures gauged by using a non-standardized method I think its pretty silly to try and make modern day comparisons using either PSI or CUP.

What type of copper did the Germans use? There is more than one type and each would have a different resistance to being crushed. How large was the crusher piston, and what was it made of?

I have read about two different set ups for a CUP measuring device. One had a hole bored in the chamber that allowed the brass in the case to blow out and act on the crusher piston...and the other had a corresponding hole drilled in the case which was covered on the inside with thin paper to hold the powder in. I cannot see how these two types could yield the same result.

I think the point here is that what the Germans in the 1800’s described as a certain pressure reading cannot be directly equated into 21st century measurements with any degree of accuracy.

Personally I find it highly suspect that anyone could measure 4000 atmosphere momentary pressures with ANY semblance of accuracy in the 1800's. The crusher method was a good attempt for the materials and manufacturing practices at the time, but trying to say any measurement of the kind from that era is comparable to modern measurements (without detailed inspection of methods and materials for sure) is a fools errand.

We know now that the crusher method is highly variable (has a lot of random error), and shaky to convert to standard pressure units.