Thanks Don M., I'm satisfied with 1935-37 time frame.
I lean toward the latter only because of the lack of the magazine safety and the documented time frame of its elimination; thus assuming any pistol reworked prior to that time would have had the mag safety added; and the salt blue finish. Though I have read no comment about salt blue use other than in connection with Mauser production.
Of course, the magazine safety addition could have been omitted earlier than 1937 orders, and the paperwork caught up later.
Dave,
on the muzzle- i just "assume" muzzles were polished when the barrel was made, the barrel may have been completely finished before installation- I can't decide when the TP/E was stamped, sometimes it looks after finish. But prior "art" dictated polishing the muzzle, for aesthetic effect- as it makes no practical difference.
I have several or perhaps many police lugers that when refinished the safety marking was not filled in. I suppose this was too much work for little effect? JMHO.