I would be willing to bet that the rifle you are looking at is of German origin. If my memory serves me, I believe the stamp means "Deutsches Reichs Gebrauchs Muster" with a close translation being "German empire protected Trademark" OR or literally "German empire of use pattern."

My father in law is Austrian and does a lot of hunting there. All of the hunters (his friends) that I have met love their "drilling rifles." That is, a weapon with up to three barrels with varying calibers. My father in law has a nice drilling that he hunts everything with--boar, stag, small game.

Hope it helps.