Thanks for details, the nr,1 and 3 was delivered with blanks by F.Koeller Solingen Ohligs,and like You already mentioned the nr.2 by Rich.A.Herder, finisher as by all Durkopp Werke Bielefeld. The last one should be postwar refurbish as visible blueing in fuller, as mentioned Weimar era used, any 1920 stamp there?