The F.ussstahl Krupp Essen, is really Fluss Stahl Krupp Essen, which means Fluid Steel made by the Krupp firm located in Essen, which is a city in the Ruhr valley.The 16s in circles mean the gun is chambered for 16 ga 65mm(2 1/2-2 9/16")shells. The 16s(no circle)show the diameter of the bore( in ga. measurement) ahead of the chamber.These numbers don't always match.If either barrel has a crown W, that means it is choked(usually pretty tightly)( maybe the Roman numeral IV is really a W).For further information, it would be helpful if you post photos of the proof marks.
Mike
