I had the opportunity to take a look at this rifle at the Las Vegas show, and I have to say it looks a lot better, more realistic, in person than in these pictures.
I would say all, or surely most all the parts started out together. The barrel signature looks fine in person, un-messed with. If the lock has been converted to flint, there's no sign of it from the exterior, and it and the breeching seem right at home. In hand, it's also a very nicely proportioned rifle.
What I think has happened was that at some point, not recently, someone has removed all the original finish from the rifle. I mean off the wood, metal and brass. I think the wood has been sanded to remove most, but not all, the dents and dings, and then a new varnish finish applied. Some of what I think are deeper original dents have this new varnish in them. There's several more recent dents in the wood, and the varnish is gone there. I think the brass and silver has been steel wooled and buffed up, and the metal stripped/sanded, and rebrowned.
Personally I think all this was done well in the past, maybe after WW II / 1950-ish, when these old useless rifles were sometimes over zealously cleaned up to shoot again.
I told Mr. Antiquegun I'd seen the gun on the forum and he had no problem with me looking at it, and in fact was looking for information.
John