Again, I have to disappoint an overoptimistic American. The shape of a crown indicated a rank in European nobility. This crown indicates the rank of a quite common Freiherr or Baron, the second lowest rank of nobility, called Gentry in England. It would have been an insult to engrave such a humble, inappropiate crown on a gun ordered by any member of a royal, dukal or even countly family.
"Hofbüchsenmacher" was a title given to many upgrade gunshops. It means nothing more than the British phrase "By Appointment to His Majesty the King", good for advertisement only. Nagel & Menz had gunshops in Baden – Baden and Strasbourg. While Baden was THE spa of the international aristocracy, Strasbourg in Alsace – Lorraine was part of the "Reichsland Elsass – Lothringen" from 1871 to 1918, a territry subject directly to Kaiser Wilhem I.
The drilling with wit the up-down swinging right hammer nose is to the early patented design by Immanuel Meffert, Suhl. So it was most likely made by Meffert for Nagel & Menz.