To add to the confusion, Mauser stamped the caliber markings on the barrel using their own code when the rifles were produced. I have seen the following stampings for the 8x60 round. The first 2 were .318 D., the rest were .323 D.

8x60 (normal loading)
8x60N (normal loading)
8x60S (normal loading)
8x60M (hotter loading)
8x60 Magnum (hotter loading)
8x60HV (magnum bombe)