Instead of increasing velocity with a heavier load to lower the bullet impact, I raised the front site. According to my math, I needed to raise the front site by 0.12" which would result in hitting 3" high at 25 yards, thus being dead-on at 100 yards. As I have done in the past on some of my other vintage rifles, I glued on a small copper hood over the original site. This copper hood is easily removed by heating with a match so that the original site is not harmed. Next trip to the range should tell if I'm successful.

http://www.buckstix.com/buckpics/8-bore-site-redo.jpg

[Linked Image from buckstix.com]

How to Hunt Wisconsin Whitetail Deer with a Cannon