I have read/seen reports or pictures of a few other "1921" property markings; in any bureaucracy
someone never gets the memo!
Perhaps even "stranger" are the 1921
dated lugers with an added "1920" property marking.
See the picture below.
I've bid on a couple 1920 dated pistols with the added 1920 property stamp, but "missed" them. How about that for redundancy, a 1920/1920 !
