I shoot the same gun and load. I swab the bore with Thompson Center's No. 13 bore cleaner then a dry patch between shots and do not have any problem with loading or accuracy. As you have found out, you need to swab the bore after each shot. Perhaps switching to 777 will help, although all i have ever used is the Pyrodex pellets. I get 2", 3 shot groups at 75 yards with this load, which is more than acceptable for the conditions i hunt under. I took two deer this year with my setup and i am pleased as punch with both the Optima and the Powerbelt bullets. Good luck!
125yds hitting dead on, went back to 190 yds, 6inch's low and 3 to the right.
I didn't have a steady rest on any shots, but i was impressed with accuracy Some of it might have been me
the first 3 shots went good for loading, after that, it was little tuff to get the powerbelt seat that last inch. I had to definatly swab after 6th shot, wayy to tuff to seat bullet,lol. 1 and 2 seated good, 3 took a little effort, but not bad.
Overall, will do good for me, its only week long ML season anyway.