You know it's a fake arm, don't you?
Noted old arms builders and experts, like Leonard Day, seriously question its authenticity. Len dates the barrel to be a far newer and of French origin ...
I don't really know one way or the other if it's a fake, the Smithsonian seems to value theirs. I just think it's a cool looking matchlock. Shockingly enough, I'm not familiar with Leonard Day either, so my opinion probably doesn't much matter.
In any event, I really like Coryjoe's club butt fowler.