Shot a .350 ball with .20 patch today, with 40 grains of fff. At 25yd standard competition target, on practice first shot flyer a fouling shot, and the other three were a tight group touching each other. The sights on this old rifle are terrible, and I will change them out. The old nipple will get changed out as well, as the caps aren't sealing tight enough. It isn't too bad to hold off hand, and with better sights should run well.
I really see nothing wrong with running an antique rifle if the mechanics, and bore are nice. My firing shooting next to me suggested to just not shoot it and hang it on the wall. Well I intend to run the rifle, and why not? I won't hurt it, and maintain my guns well.