I gave all my extra power belts away. the plastic fouling was terrible. I could only get two shots before I had to use a hammer to get the the third in. I was using 777 and 245 gr power belts. the fouling was a real bear to get out.
Two shots without swabbing is plenty when using tight-fitting sabots or Powerbelts. If you are getting plastic fouling, it's probably due to a rough cut bore near the breechplug. Shooting a box or two of full-fledged conicals will help smooth that out.
That is not the Powerbelt's fault. Some muzzleloaders need a break-in period before using sabots or Powerbelts. Rough edges on the rifling need to be smoothed-out or removed first. Also, that Powerbelt skirt was not designed to take the heat of 777 powder when using 120-150 grains. Powerbelt bullets came first on the market -- then 777 powder afterwards. Again.... that's not the Powerbelt's fault here.
But kudos to you for switching anyways. Those bullets are expensive per shot - plus have a tendency to fragment when impacted with bone. The only Powerbelt and Powerbelt skirt I trust for hunting purposes are the new Platinums. Platinums and their newly designed skirt can withstand 777 heat and bone alot better.