Just to catch everyone up, The markings include the Reich Adler over N, which was the mark for smokeless proof of guns of all types, under the 1939 Proof Law, used from 1939-45. There is also a 12/70 which means it is 12 gauge with 70mm (2 3/4") chambers. It has the "Sole & Pick" house mark for the Suhl Proof House, as well as 440 meaning it was proofed in April 1940. There are also an R and S which I think are touchmarks of workmen and a partially obscured mark that reminds me of the provisional barrel proofmark under the 1891 law, used until 1939. The barrels may have been provisionally proofed in 1939, then finished and finally proofed in April 1940, but I can't be sure.
Mike
