Importer stamped anywhere, like maybe Von Lengerke & Detmold? The "Prussia" should definitely put it pre-WWII; not sure when they stopped using that.

No date code on the barrel flats? It'd be 3 or 4 digits, month and year. My guess would be not all that old--as in no earlier than the 1920's--because of the 2 3/4" chambers, unless maybe they were lengthened and someone restamped the gun.