Right, and there is a fairly wide range of sabots and as different manufactures tend to make there barrels a bit different in size. most Knight barrels tend to be a bit on the loose side which means the black harvester or the MMp hph24 [same thickness] or the MMP 12 often fit best. If it slides down easy it might come off the powder and act as a barrel obstruction. If you can push it down with out much effort its to loose for good accuracy most of the time if it takes both hands and you have to put a bit of effort into it it will probably be in the right neighborhood, if its so tight you would like pound on it with some thing then it is too tight and will likely not shoot good. Hope this helps. You might get on Modern Muzzle loader Forum and go to inline muzzle loaders and look at the sticky on bullets and sabots they have it well laid out. Lee