My approach has always been to work on my rifle and handloads until I get 3/4 to 1/2 groups off of the 100 yard benchrest. I want as much margin for human error as I can get. Then I practice off-hand shooting until I know the distance I can keep all of my shots inside the kill zone. That is my maximum distance for that rifle in ideal conditions.
I shoot a lot of competitive off-hand matches with a flintlock rifle. Believe me when I tell you, if you can shoot a flintlock well, you can shoot anything well.
