For a first time blackpowder big game hunter who cannot use an inline and is not looking for a traditional experience I recommend the Lyman Deerstalker. It comes in stainless if you like, and can be enchanced by equipping it with the 57SML receiver sight, where lawful. The .50 will do nicely, especially if you use bore diameter conicals, and is the best supported bore diameter accessory-wise. (My Encore 209x50 really likes the 295 grain Powerbelt and two 50 grain Pyrodex pellets.) My roundball gun is a .54 caliber flintlock Lyman Great Plains rifle. It is a great value but its curved steel buttplate and my shoulder don't really get along all that well.

http://www.lymanproducts.com/lymanproducts/rifle.htm