Those rifling pitches are almost certainly for the picket bullet, a short, conical bullet shot with a cloth patch, and not for any sort of cylindrical bullet with lubricant grooves intended to be shot naked.
Many early target-type muzzleloading rifles were made for the picket bullet, and are often fitted with a false muzzle to aid in starting the patched bullet straight. In any case, the muzzle of a picket gun is normally recessed for the patch, and a 'guide starter' is used for the same purpose - to start the bullet straight in the bore: the body of the starter is recessed for a close fit on the rifle's muzzle, and the nose of the plunger is shaped for the bullet used. These methods of loading are critical in keeping the bullet from tipping in the bore (because it has virtualy no cylindrical body to keep it straight), which spoils accuracy.
Some photos of the rifles, and particularly the muzzles, would help in determining how they are intended to be loaded.
mhb - Mike