In your post on the other forum you asked if your Luger was a 1902, to which I replied that a 1902 would have a 5-digit serial number whereas your example has just four, therefore a model 1900. However, model 1900 Lugers were produced into the 5-digit range before 1902, the 5-digit serial numbers did not begin with the 1902 model. I was just trying to point out that your example could not be a 1902. A bit confusing, but Lugers and their history are fun to sort out.
Ron