"How far can I reach out and touch a deer under these IDEAL CONDITIONS that will never happen."

The problem with long-range shooting with a black powder weapon is not accuracy, but knowing the trajectory intimately and being able to estimate ranges precisely - within +- 20 yards or less.

If you have a rangefinder, and have time to use it, the problem gets simplified some, but you still must zero your rifle in at a realistic distance, and then shoot it a lot at various distances to find out exactly how high/low your bullet is going to strike at that range. This shooting has to be done with your powder and bullet combination. Guessing and printed charts will just not do it!