DWM Luger age question

I own a DWM luger P-08 with the 150mm barrel that I estimate was manufactured around 1914, but that's just a guess based on it's markings.

It has a 4 digit serial number of 7490 and 90 stamped on the other pieces. There is no date stamped on it anywhere I can find. I heard that serial numbers were reused on Lugers and the date stamped on the top of the receiver by the barrel, but mine has no such date.

Anybody have any idea how I can find out the the date of manufacture or more about this gun? BTW - when I bought it, it was very dirty with actual dirt/earth. It cleaned up very nicely and shoots flawlessly. It amazes me how a near hundred year old piece of machinery can work as well as day one.

Any information would be greatlly appreciated.

Thanks!

Check the number on the frame again. See if there is a letter under the four-digit number. That will determine the time frame of that series.
B

Due to the numbering system of the military Lugers, pictures would be necessary to tell you anything about the pistol. Is the barrel serial numbered to the frame?