Could be a cleaning problem. The CVA's have much rougher barrels than the knights and encores from what i have seen and collect that plastic easier from Sabot or lead from conicals. I used JB Bore cleaner which is abrasive to get out all of the plastic from past Traditions. Made alot of difference. Very hard to wear out a Muzzleloader barrel. Especially since the pressures don't reach past 30KPSI and velocity is so low. And bore is so large compared to 65Kpsi and small bore of a 22-250.