The old and very popular 375 NE (2-1/2 in) may have originated with Holland, but it was widely used in the gun trade. When Holland brought out the 400/375 for their highly modified Mannlicher-Schoenauer rifle in 1905 I guess it created some envy because here was what a lot of folks thought was the hottest bolt action going loaded with something that gave the velocity of a 303 (better actually) with the diameter and bullet weight of a more substantial medium bore thumper.

The 9.5 x 57 mm Mannlicher Schoenauer, introduced in the Model 1910 rifle, may have been designed by Westley Richards, not Steyr. I think it was brought out specifically because Holland controlled the only rimless 375 on the market. And of course only a year after Westley Richards duplicated their 400/375, Holland trumped that by bringing out the 375 Belted Rimless Magnum Nitro Express (better known as the 375 H&H to us today). The big magnum 375 is what killed the smaller 375s, not any lack of performance. These cartridges are all in the same class as the 348 Winchester, 358 Winchester, 9.3 x 57 mm Mauser, etc, which is to say they are serious medicine for nearly anything.

My brother is rebuilding a 1910 MS for me right now and I will post a web page on the project when it is complete.