Thanks for the photos. Obviously a Gewehr 98-based rifle. Newly made in the late 30s or converted - not quite sure, but I don't see any obvious signs of scrubbed markings on the ring of the action body, so I tend to "newly made, using Gew. 98 parts".

If you want to fire it, then the 8.15x46 material will be available somewhere. This cartridge may be considered to be the Germanicon equivalent of the 32-40, filling a similar "ecological niche". For target shooting at 100 meters, maybe small- game hunting, but not sniping at 1000 yards!
I would be interested to see how it shoots. Will you try it out? The major problem will be handling it without damaging the stickers.

An amazing find.

Patrick