The only thing I can say is that I like the action on the Mauser, but the Russians did beat the Germans carrying the Mauser! Now that might open a whole other can of worms, but you got to hand to the Ruskies!!!
It's the fighting men's spirit more than the tool used at play in that conflict.
It would be different if it were repeating rifles against single shots, or muzzle loaders... then the tool would be the deciding factor. The Comanches with their bows and arrows totally dominated the plains until the rangers acquired the repeating Paterson Colt pistol, then the Walker. That tool pretty much turned the tide.
My dad was in the Philippines in WWII, and had a couple of civilian brothers fighting with his company. He said they had one rifle between them. They got trapped under a bridge by several Japanese soldiers, and managed to rejoin my dad's unit shortly afterwards. The enemy soldiers did not. He said that one rifle sounded like a machine gun with those two brothers working it.
It's not always the tool.