Not all military or police pistols received the "1920" property stamp.
Many had no police unit markings.
I've done several threads on the mag safties , one not too long ago- try a forum search for "magazine safety".
http://forum.lugerforum.com/showthre...agazine+safety
If I spot it I'll put in a link here; but you can do a lot of informative and enjoyable homework on your own by using the search feature and reading the stickys and FAQ.