Good catch, I was about to chime in and add that my early 1906’s, a model AE (still sits on a long frame and BUG proofed) as well as my Brazilian Contract gun, also have polished instead of Gesichert.

Thanks for that update Doubs. I think we are all on the same page now. I now know there were at least a few example variants of model 1900 with GESICHERT! Prost! :cheers:

1900 Lugers
 

I thought I would share this info as I was not familiar with the cited book.
So on Facebook there there is a Luger Collecter's Forum. Just today someone in Belgium post pictures of a 1900 Luger, not American Eagle, with a five digit serial number 21023. Safety lever grooved but posted in down position so you can't tell if relieved.

Another individual then posted pages from an English language book that stated the total production of 1900's was 21,220.

The poster said the pages were from book:
DMW Pistole
Parabellum Luger
1st Edition

author Jesse L Murray