I honestly think that your desire for a long range kill is clouding consideration of hunting ethics. IMHO a 180-200 yard shot with a round ball at black powder velocities over open sights is asking for trouble even if you're able to ACCURATELY sight your rifle in at that distance. In the time it takes for you to pull the trigger and the ball to get down range, the deer only has to take one step for a gut shot animal that will run off. By the time you reload and cover the distance to where the hit took place, that deer will probably be long gone, leaving little blood to follow. As stated above, shooting at a cardboard target at a known range is different than shooting at a live animal who doesn't feel compelled to cooperate.