I tried a little experiment on the old Knight. I pulled the breach plug and started some FPB nose first into the muzzle found a short starter that fit the back end and pushed them in about 4 inches. Then I took the range rod and pushed them back out again; this sizes them to that particular gun and relieves the loading problem considerable.
Matt 068, The real importance of having the right thickness of sabot for your particular gun can not be over emphasized because it is on of the things that a lot of people create their own set of problems on. A lot of us that have been shooting sabots ever since inlines became commercialized find the right sabot that will shoot good in a particular gun and buy a large quantity. Since there is a large tolerance on muzzle loader barrels no one can predict which particular one will work on any gun.
as a general rule TC guns have barrels .500 or a bit under, Knights often are .500+ whites are .502 to 504 and while the Bergara barrels run around .500 the others used in the lower priced brands run from .497 to .503 and there are lots of exceptions to these rule of thumb categories.