Is it? I thought the M-S was a little shorter (case) than the Mauser version - and also a small difference in head diameter (?). I will grab some of my old factory 8x56 MS ammo and measure it.
The 9.5x57 MS and 9.3x57 do differ slightly (in bullet diameter and case length) and I think the confusion arose when people were using Mauser cases to form 9.5x57 MS (or .375 Rimless NE for British colonies) when it became more scarce. Other confusion between the two could be because the performance was nearly identical.
I regularly hunt with a Winchester P14 .303 Brit, Gewehrfabrik Danzig small-ring M98 sporting Mauser 8x57 with double set triggers built in 1919, Gustav Genschow & Co large-ring M98 sporting Mauser 9.3x62 with flip sights from the 1920s and a Savage 99F take-down in 300 Savage from 1924.
I've bought so many new rifles but I just can't seem to keep these particular ones in the safe. The cartridges work way too well and the craftsmanship is superb. They just handle and shoot way to nicely to not use them on game. Oh yeah, and not having a bulky scope on the receiver sure is nice for pushing through the bush.




















































