I know nothing about guns of this era but that is what I thought when I first saw it. The mechanism does work and it appears it could be fired with some work. (not that I intend on doing that) If it's a decoration, it must be an old one that was handled and played with a lot.
I'd suspect its structural integrity has been compromised beyond ability to restore, and if it were mine, I'd clean it up and polish it up as well as possible and then mount it in a frame for display on my wall.
A lot of the "antique dealers" in the bazaars and souks around The Middle East and Turkey, etc use an old part or two to construct souvenirs. The barrel looks like it might be genuine, but the folks in those places are also well versed in casting, and they may have made a cast of an original barrel in a material not good for barrels... but easily melted and cast so good for souvenir making. The lock looks to be a copy of a Spanish miquelet lock, and has the grooves on the Frizzen face, which seem to be soldered into place. That's a detail unneeded in just a souvenir, so might actually have been some sort of old lock as well. The point would be to make it look very old and get a good price for it from a tourist.
The bore of the barrel is pretty rough and appears to have casting lines down both sides of the bore so you may be correct on this.
