Shotgunjones,
The gun was made before the "Mall Mart" and "Interior Net" came about, and many makers made their own reamers as well as loading the ammo for the rifles they built. This more or less insured repeat ammo sales. We complain now that many of these old rifles are not marked as to the cartridge it used. The one that made it knew what it shot, so the owner had to go back to him for ammo. It wasn't until the 1939 Proof law that German guns had to be marked by the common name of the cartridge it used.
Mike