A very nice gun indeed! Unfortunately, this is not a royal crown, but that of a baron with the initials FS.
Emil Martin also was building guns with knob triggers similar to those of Johann Reeb. It was Martin, who claimed being the designer of some guns and rifles with Knopfabzug for emperor Kaiser Wilhelm II who was handicapped with a crippled left arm and had to shoot with one hand only. The whole story:
http://www.hunting-heritage.com/blog/index.php/2016/05/23/push-not-pull-a-rare-ou-of-e-martin-bonn/Waidmannsheil,
Wolfgang
