I had the exact problem with my CVA Kodiak Magnum. After each shot I put the brass cleaning jig on my range rod and run it down the barrel. I usually can feel the crude ring. I bust up the crude ring with the brass cleaning jig then run two wet and two dry patches down the barrel. Pain in the &^% to do, but the accuracy is great and never had a problem with seating again. I have loaded a second load without cleaning just to test and the accuracy did not suffer to much. I figure I can get a second shot in the field and be accurate without cleaning if need be.
I also wanted to experiment with different powders to see the results. However, in my first attempt APP sticks I only could get the gun to go off 3 out of 5 shots and the accuracy was horrible. I would rather clean the777 then wonderif the gun was going to go off. I have heard the powder form is usually cleaner then the sticks, but I like the conveinence of pellets.