I am not familiar with a gunmaker named Rugg, and can't help with identification.
Please don't take offense, but this is a discussion board and I have a couple of comments. The hammer looks a lot like something that might be found on an Italian lock (e.g. Pedersoli), but if the pistol were a kit build, the barrel would probably be covered with graffitti, which it isn't. I think Dixie Gun Works used to sell a lot of imported locks, so the lock may have been from them. Also, the nipple isn't quite centered in the hammer cup. However, as long as it pops a cap, you're good!
Mr. Rugg did a good job inletting and finishing, and it is a very good looking pistol. Nice find! Enjoy it!
Best regards,
Notchy Bob