Thanks, but not sure handloading would cure anything, since the dimensions of the rim would still be the same. The rim on the cartridge is a few thousandths too large in diameter or thickness to fit the mag and the extractor, at least when I try to put a cartridge in the extractor by hand. If the rifle would feed from the magazine, maybe the camming power of the bolt would be enough to grab the cartridge. the cartridges seem to fit the chamber just fine.

I've sent an email to the german arms collectors group to see if they have any information. I also checked the numbers on the bolt, etc. - everything matches, so it isn't an issue with a wrong bolt, etc.