Re: German Drilling - What's It Worth?
Krupp stahl means Krupp steel, high quality steel. The Nitro means the gun is suitable for smokeless powder. The shotgun barrels are 16 gauge, the rifle barrel is 9.3x72R.
Fleischmann is the barrel maker, Neundorf the gun maker.
The crown S, W, and U are proofmarks, respectively for smooth bore barrels, choked barrels and definitive proof. The crown G and E are proofs for rifled barrels and "express" (high power) rifled barrels. K m G N 13 gm means the barrel was proved with a 200 grain copper jacketed bullet using Nitro powder
I won't give value, but will say that that drilling is a very nice one and should be quite valuable. You might check auction sites and some of the sites devoted to double guns and drillings.