That's a West German (thus post-WWII) gun from the proofmarks. Might also say "Eckernforde" and "West Germany" on the barrels. Appears to be a Sauer Royal, the highest grade W. German Sauer imported back in the 50's and 60's. (But it'd be more of a medium grade across the entire spectrum of Sauers.) Nice, stout gun. You shouldn't need to worry about what you shoot in it.