I cut them in half and file down a jag for a snug fit. On the swivel handle you can work the bore pretty hard without removing enough metal to hurt anything. Again, work from the breach to avoid crown damage, shove a plastic straw into the shroud to avoid losing one in there.
Fire lapping using ringed pellets and the liquid equivalent (the milky bore cleaners, Remington "lead remover" is one) is by far the best of the"simple/easy/safe" methods. The liquid polish removed very little metal, and it's mostly worn out by the time the pellet gets to the muzzle, so your risk of an oversize bore there is virtually nil.
The advantage of the rod techniques is feedback, you can tell what's going on. With fire lapping it's a matter of shooting a dozen polish loaded pellets, cleaning, shooting enough to lead the bore, and testing, repeat...very time consuming.