There's a lot of different powders, sabots and bullets to try out. Most recommend using loose powder instead of pellets and swabbing between shots. Some might even recommend using certain primers like the Winchester 777's.
Most of the bulk sabots are made with slightly different diameters which have different loading and shooting characteristics. To learn more about their differences, visit these these 2 manufacturers websites for details:
http://www.mmpsabots.com/
http://www.harvesterbullets.com/
But if you want some specific tips from seasoned inline shooters who may have knowledge about your Knight rifle, the folks on this black powder forum will be very helpful:
http://www.huntingnet.com/forum/
You can learn a lot just by reading their posts and asking a few questions.