That's what I thought: the town mark ZEL and the Saxon coat-of-arms (in the 17th century, Zella belonged to Saxony while being part of Thuringia today), two marks that are identical on my musket and can be found on all guns from that Zella series, prove that this originally was a plain military musket of ca. 1645.
The riddle has been solved - sorry for the bad news, Raf!
As for the question mark in your title: yes, this once was a genuine 17th c. matchlock musket, the stock however prettified later-on, and in an earlier style than the rest of the gun.
Btw: the fire shield as well is a fantasy addition - please refer to the fire shield on my gun.
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