Although you don't see patch imprint on the lead where the grooves go, you likely get enough obturation (sp?) of the ball upon ignition to seal your bore, and thus have no blow by. This is good. But your patch isn't carrying enough lube to dissolve the fowling from the previous shot, all the way to the charge. So you are getting fowling build up at the breech. Or you aren't using enough lube! I shoot a .60 cal flint rifle with a 42" bbl using 86 gr. FFg GOEX and a .590" pure lead ball with .020" patching, and I never have to clean during a day's shooting. Even so, when I'm on the line target shooting, and there is a break in the shooting, to change targets for example, I always load my rifle right away, then wrack it. If I wait until the line is clear for then next relay, IO will have trouble getting that first ball down the bore over dried out fowling. My patches are soaked but not dripping...I prelube my precut patches and store them in a tin with a hinged lid. I'm sure you can get good accuracy with between 80 and 90 grains of FFg GOEX...I sure can. I recently returned home from an annual rendezvous where all the shooting was at paper. The rifle match was 25, 50, 75, and 100 yards, all offhand. I placed first with my old Chambers' (Mark Silver) Virginia rifle described above.