I think the S. Mg. is for Magdeburg District, but what unit is the 675? Or is it a unit at all? Any help would be greatly appreciaterd

I am fairly certain that the "675" is the individual weapon number.

 

If you are interested there is this website:

 

https://oldmilitarymarkings.com/police_unit_marks.html

Thanks for the information. I was using that website you mentioned to identify the S. Mg. (Magdeburg) part. Just was puzzled about the 675. I didn't know if it was a unit, or just a rack number. Seems to just be an individual weapon number. Maybe I was trying to read more information into it than it really was.  Again, thanks for your confirmation. I really appreciated your help. Dave

My pleasure - always spread the knowledge!