For some reason, the paper above the ball has no effect on accuracy. Perhaps it's shed upon the ball leaving the muzzle. A friend has a deeply radiused grooved .75 and cannot shoot more than 3 paper ctgs. without wiping the bore due to fouling buildup in the deep grooves. My barrel, with 'square' rifling, has no such trouble - 10 being as accurate as patched round balls, which is excellent in that rifle - 1 1/2MOA and gives the same velocity as patched round balls too - 1,550fps, with the load I use. This shows little or no gas blowby. They are snug as noted, not loose as in a military ctg. To get it started down the bore, you have to choke up on the rod so only the brass tip is out of your hand. A quick shove puts the ball down that far. Once there, about 1" below the muzzle, it can be seated on the powder in one push.
I thought I might try dipping the ctgs. in some sort of lube, but a lube soft enough to be of any use in softening fouling, would rub off as well as pick up lint and dirt from my pocket, so that experiment didn't go any further than thinking on it. Being able to shoot 10 shots without diminished accuracy was good enough for me.
I haven't tried ctgs. for accuracy with light loads, only the heavy hunting load. Light loads don't shoot well past 50 yards in this rifle, anyway. It take additonal powder to shoot well at 100 yards and beyond. Witness Mark's chunk targets - .50 cal, .495" ball and 90gr. 3F, equivalent to about 110gr. 2F & that was only 50 yards.