Vern,
I took a short interest in Simson Lugers (sorry, Ed...) over on Jan's Gun Boards in this discussion thread...
Mostly notably about the variation in toggle marking, shape of lettering and placement of proof stamps.
There is a pretty good photo-collage on the 2nd. page of this discussion :
http://luger.gunboards.com/topic.asp?TOPIC_ID=10479