Here's the rifle I had.
The "MAGNUM" was a bit messy like it was double struck but surely an original Oberndorf mark.

Same as marks on 8X60 MAGNUM rifles.

I believe that the "magnum" name was simply because this version was a higher velocity as Daryl mentions. The bullets seem to be spire points as well and my rifle had a layer of rubber in the front of the magazine to protect the soft point bullets in the magazine. I had seen this only in one other Oberndorf '98 and believe it to be original from Mauser.