Thanks to all for your kind comments!
Dave, I really have no idea how many hours I put into this--I did this at a leisurely pace over several months while working simultaneously on other projects. The wood repairs probably took the equivalent of a few days--I probably spent more time putting together the lock.
James, I'm aware of the weakening effect of ammonia fumes on brass, and I wouldn't have used ammonia on a piece seeing active use, or on a part likely to be stressed. Since this one will probably only hang on a wall, I was less worried. Before using the ammonia fumes, I tried to color those parts using cold blue, brass black, and liver of sulfur gel. None of these resulted in a patina that matched the original brass parts. Only the ammonia fumes came close.
Singlemalt, I doubt that I would make a bench copy of this rather plain export gun--although I like the old gun, it's a little ordinary for my taste. I recently made a much fancier American fowler, stocked in British style, that I found a lot more interesting. I'd post my pics of this piece from a previous post, but photobucket killed them.
Thanks again to all!
Gregg