The reason there's a W (Würgebohrung)only on the LH barrel is that it is the more heavily choked. The U (Untersuchung) is an inspection mark after proof firing. The S stands for shotgun (Schrotlauf) supplimentary proof. These marks with their Imperial Crowns and Eagles were only used by proof-houses in Germany between 1891 and 1939.
I can't say that this is true for a couple of reasons:
1. Whether each tube is lightly choked or heavily choked, if there is a constriction greater than 0.2mm, then the tube should bear the "Crown" over "W". This mark notes that the choked tube was subjected to an additional proof vs. a tube without the mark, which the diameter is measured at the muzzle.
2. The stamp of "Eagle" coupled with "Crown" over "S" noted the smoothbore tube experienced the 1st or preliminary black powder proof. A tube had to fall within 2 categories: rifled or smoothbore. If the tube was rifled, then one will see an "Eagle" coupled with a "Crown" over "G" and if smooth, then the "Crown" over "S" accompanies the "Imperial Eagle". Post 1939 when semi-smokeless wasn't readily available, the combination of "Eagle" "Crown" over "U" was used. In East Germany both marks of "Crown" over "S" and "Crown" over "U" accompanied by the Imperial "Eagle" took a sort of hiatus or sabbatical from 1945 - 1950 as both East and West Germany adopted a material proof, which at some point could have been just an inspection. West Germany went their own way in 1950 and continued the divergence in 1952 with vastly different marks. East Germany returned to the old ways in 1950 and continued to use the Imperial "Eagle" accompanied by the "Crown" over "G" for rifled & "Crown" over "S" for scatterguns as the 1st black powder proof until circa 1970. I regularly use a BUHAG and have observed several other East German double from the mid to late 1950s to 1960s and the mark of "Eagle" "Crown" over "S" is present on the tubes. Past 1970 for now I really can't say.
Kind Regards,
Raimey
rse
