... Post 1968 the letter convention was to be used but I don't think all subscribed. Don't know when or if the Jahreszeichen fully converted back to numerical but after unification I think the Jahreszeichen went back to letter. It may have been an attempt to prevent the easy ID of the year of proof and inject a bit of haze as to how long a sporting weapon had been in the shop. Anyone have a post 2000 with proofmarks? Also remember that I/J are one. ...
Well, that can resolve the mystery. My Simson has "1079" on the barrel flats, so at least as of October 1979 Simson hadn't signed on to changing to letters.
As noted, ground truth would be to contact Merkel, but this is much more fun.
