A few more suggestions George

Run a couple of cotton balls down the barrel -- then back up to check for fibers with a bore light/AA flashlight. You may need a barrel lapping if rough spots are in there.

Also, check your used range sabots to see what condition they' re in.

Also, check your front & rear sights for even the slightest looseness.

Also, check for uneven bite marks or gaps where the stock meets the barrel -- left side & right side.

I am not the greatest muzzleloading mechanic on this block.. hopefully one of these ideas listed above will get you closer to the bullseye. Maybe someone else reading this can offer more opinions.

If none of these work & you remain unsatisfied, contact Knightrifles.com... they have an excellent service staff.