We finally found a place to shoot it, in Prince William County VA. Here are the ranges we got with a 93 lb. ball. We used two patches made from moving blankets since the bore is about 9.5 in. and the ball is 9.1 inches. A number of people told us we didn't need any patches but with that much windage, we were worried about denting the bore of the weapon, since we're using a steel ball.
Ranges achieved with 93 lb. steel ball, Goex FG black powder, friction primer ignition, tube at 45 degree elevation:
Shot.........Charge, Oz........Approx. Range, Yards*
1.....................4...........................25
2.....................6...........................43
3.....................8...........................66
4....................10..........................92
5....................12.........................137
*converted from paces
Video, about 10 min.
http://www.youtube.com/watch?v=nVj-3Rzsu8M