Currently using wingless RWS percussion caps in my Model1863 Rebel Musketoon(brass furniture). This Musketoon has a .574" bore with rifling depth at the muzzle at .003" deep for all 5 grooves. The rifling depth at the breech is .011". I was concerned at first that the deeper groo ves at the breech would allow flame to burn my patches - I submit the balls MUST be obturating as they actually seam to seal the gasses behind them - recovered patches are perfect - re-usable and do not even show scorching along the groove marks. Accuracy is 3"(5 shot groups) at 100 yards off the bags - which surprised me due to the short sight radius with the military sights. I shoot 85gr. 2F GOEX with a 10 ounce denim patch - or the .023" 'railroad' mattress ticking.
I initially started off shooting a .575" ball, but they were a big snug in the .574" bore with the 10 ounce denim patch as you can well imagine. Note, 10 ounce, not 10 thou.
My .570 mould, which case .574" balls, would just pass into the bore at the muzzle. A friend's .575" Shilo mould cast balls that would all sit on top of the crown.
I've never had a misfire with that little gun, nor clogged nipple passage. I never expect to. I shoot from 50 to 100 shots in a day, no wiping- ever while shooting. I currently use a .562" ball with the same 10 ounce denim or .023" 'railroad' mattress ticking patch.