Back to DWM versus Erfurt...
I noticed that the tooling marks on the rear inside part of the frame (just below where the rear pin holds the toggle assembly to the receiver) is different.
The tooling that made my DWM 1916 Luger left round marks. The tooling that removed metal in this area on my 1917 Erfurt is squared.
It's apparent that the milling technique used by the two manufacturers was different.
I've posted a quick study with photographs in this forum at:
http://forum.lugerforum.com/showthread.php?t=24367
Marc