I agree with Pawpaw. It appears to be a German proof mark (Crown over U), the standard proofmark of Germany circa 1891-1939.Pawpaw wrote:That appears to be a German inspection mark (1950 & later).
Look on page 6 here: http://www.nramuseum.com/media/940944/proofmarks.pdf
http://www.shotguns.se/html/germany_1890-1945.html
https://thefiringline.com/forums/attach ... 1201457688
As to who made it and when is anybody's guess, if you don't have any other marks to help identify it.
Hope this helps.
