You could have some rough spots in the bore that snag the patch. Or maybe even a slight bit of rust.
Buy some Flitz (Polishing conpound) some 0000 steel wool and do about 50 to 75 passes. This will smooth out anything in there. All of my muzzleloaders get this process.
I believe you have a CVA Mountain Rifle from the sound of the USA made barrel. That will be a Douglas barrel and i am betting its the typical Douglas, rough rifling that they are known for.
I have a .54cal.