Still MORE research! This is what I have found, regarding the "oversize" chambers on some 7mm Rolling blocks. It may or may not be true, what you read isn't always true! I had read all of my life that the 250-3000 AKA the 250 Savage was the first commercially loaded cartridge to exceed 3000 FPS; when in reality it was the 280 Ross in 1907. But I am straying.....
Apparently there WERE two 7mm rounds, the Spanish and the German. The difference was about .010 in length (and headspace). The 1902s were chambered for both, according to which country ordered them And they were marked; the Spanish chambers were marked with an "s" behind the caliber stamp on the barrel. All others had no mark. It is pretty much impossible to tell who the guns were made for, except for the rifles made for the Mexican Government; these bore serial numbers. All others did not.
My gun has a normal chamber and does not have the "s" stamp. Barnbwt I would guess that your rifle also does not have the "s"
I don't know if the above is true or not but it DOES offer one explaination to this little mystery. The Spanish Mauser rifles would have had no trouble digesting either round, the extractor would have held the round against the bolt face, something the Remington's extractor can't do.