Hi Dave
Congratulations. Nice find. Which may turn out to be even more interesting with a little more investigation. This piece would be worthy of some additional photos: Top view, bottom view, inside the lock details, pan/vent hole area, trigger guard, etc. There may be a letter or number on the inside of the lock plate.
The amature engraving on the barrel appears to have been done at some point after the gun was built. Possibly by a second or third owner during the period.
But in any case, the cresent moon and fish are an indication of Ottoman/Turk ownership at some point. As Dale mentions, the two marks are more likely a builder's mark. Possibly just the barrel. Most of these pistols were generally unmarked, or given a false/spurios marks. This is so that the gun would not be traced back to any paticular shop, as these guns were sold to both friend and foe alike. Some questions if you would:
Is the iron ramrod the same length as the barrel ? Or is it considerably shorter ?
Is the trigger guard attached to the stock with screws ? Or simply nailed to the stock ?
Besides the barrel tang screw, the forward part of the barrel appears to be pin-fasten to the stock. Is this correct ? I don't see any evidence a barrel band(s) were ever in use.
Is there any sign that the grip/wrist area originally had checkering ? Maybe now worn down ?
Can you take some photos of the inside and outside of the lock itself ?
I know I'm just full of questions. LOL But this example may turn out to be of even more interest than most.
Rick