I found a Swedish Mauser stampings website:
Apparently no-one except the Swedes stamped the crown.
here's a list from the nra museum on interpreting proof marks for armories from Belgium, Spain, Germany, France and Britain. Every country listed used some type of crown as a proof mark at some time.
http://www.nramuseum.com/media/940944/proofmarks.pdf Wouldn't be too surprised if every country that had both a monarch and a proof house used a crown at some point in time.
