R.Marshall,
The rifle was proofed at the Suhl proof house during Feb. 1936 as an 8.15x46R( aka 8.15x46 1/2R). The duty bullet was shown as 11G Bl G, or 170 grain lead bullet. It was nitro proofed and had a scope mounted in claw mounts. This leads me to believe it was frequently used with the 9 gram copper jacketed ( 151 grain) flat nose "express" type bullet. This loading would have been legal for hunting Roe deer. If it had been legally rechambered in Germany, it should have been reproofed and the new caliber shown. Therefore, since it doesn't have a crown R and 52mm (52 1/2)case length shown, I believe it was rechambered in the US rather than Germany. I opine then that it was rechambered to 32-40 Win/Ballard. Whether it was intended to use original length or 30-30 length cases can only be answered by a chamber cast. Since it has been performing well with 30-30 cases and lead bullets, I don't see much reason to change. If you feel the need to use jacketed bullets, you should insure they will easily fit into a case fired in the rifle and not resized. It may or may not be necessary to resize the bullets to accomplish this. Lead bullets are not especially critical in this regard. Regarding your question of why the handloader questioned the name of the cartridge. It is likely that he didn't find a perfect match of case lengths, rim diameters, or bullet diameters and just chose the closest one to call it.
Mike