2 Date WW1 Erfurt Luger Help

[BlackBart]

OK, just bought this and no doubt grossly overpaid ($1100.00) BUT I wanted one and they are getting harder to find at shows and auctions. Has some extraction problems, spent casing goes square against next round in chamber. Conical Winchester factory ammo, will soon try others. I'm thinking maybe stretch the extractor spring a fraction? On the plus side the pin hits the primer with authority.
2 aftermarket magazines, and one grip is non matching.... everything else seems to be # original. Bore is fair, bluing speaks for itself and I know it's OFTEN asked but dumb it down for me.... why the 1916/1920???
Thanks in advance!