DRP Mauser and the SS

Greetings,

My wife's grandfather brought back a fine DRP mauser. I have heard rumors these commonly found thier way into the hands of the SS as a way to get around the treaty of Versailles and never saw a postal facility...

Does anyone know of any validity to this story? I know he was in the mix with SS during the bulge and also involved in a railway attack....I have been trying to determine where the most likely place he may have picked it up???