I went and bought some Birchwood Casey Bore Scrubber. It seems to have helped with the powerbelt bullets down the barrel a lot. As for the 300gr. TC Mag Express Sabots, it has helped a little bit. Not as forceful as it was. I shot it yesterday and was able to load the TC Mag Express sabots and get it sighted in. I cleaned after each shot with the bore scrubber until the barrel was clean and dry. It shot well at 50 yards to get it on paper and out at 100 yards it was "dead nuts" in the bullseye I am using 85 gr. of loose 3F Goex for both bullets, while the TC sabot grouped tight and in the center of the target, the Powerbelts shot 6 inches high and 4 inches right from where the TC bullet was at but also in a tight group. I think I'm going to stay with the TC bullet though. I may also pick up some JB Bore paste it give it a go of that as well. Keep us informed of what happens with yours.