1. Falun is a town in Sweden.
2. "U under crown" is a German proofmark. Here we have "U under star", this is the pesonal mark of a Liege, Belgium proofhouse inspector.
3. Despite the germanic name, "Neumann" never was a German gunmaker! There were instead three gunmaking companies named Neumann in Liege, Belgium.
Neumann, Ernest, 1890 - 1905
Neumann, Max, 1924-1946
Neumann, Freres & Cie (brothers and Co)1860 - 1954
Krupp steel was of internationally renowned quality. Krupp sold barrel blanks to all European gunmaking centers, Suhl, Ferlach, Liege and even London. Jeffery's first .600 Nitro Express db had Krupp steel barrels!
So there is no hint that this gun ever was in Germany!