L. Akers - my take on it as well. The further down range the ball gets before it takes on a spin and curves "off into space", the better.
I have not tried dimpled balls, but feel the balls from a Tanner mould, without a sprue, are more accurate (or should be more accurate) than balls cast in moulds with sprue cutters. The lack of a sprue should eliminate the opportunity of the wind or the ball's balance setting up a spin. Once spinning - off they go, up, down, or to a side or any combination thereof.
I have observed, through binoculars, balls heading straight at the target, only to spin off in an exponential trajectory, shaped much like a trumpet's horn, missing by up to 3' at only 100yards. The load used by that fellow, was 65gr. 2F in a .62 smoothbore. When Taylor shot his long barreled 20 bore using 80gr. 2F, the balls seemed to have fairly normal trajectory, with none flying off in the trumpet shaped curved flight. This may have been due to the added speed, or merely coincidence, however, Taylor, using 80gr. or me using 85gr. usually have no difficulty beating the more lightly charged gun, even though that gun is shot weekly (yes - EVERY week), while our smoothbores spend most all of their time in the locker, used on the trail only a couple times a year.