Hi,
Welcome to the forum...
Your DWM was manufactured by Deutsche Waffen und Munitionsfabriken
http://en.wikipedia.org/wiki/Deutsch...itionsfabriken
The original manufacturer of the Luger.
It could be rare, or it could be very common. Pictures and better description will help. It's probably an Alphabet Commercial, which is fairly common.
You'll find all the facts you need on this website.
Marc