I know Daryl recommends using a 320 grit emory cloth to dress a crown with, well, I don't have any and here's what I have been doing as an alternative and it seems to work well for me.
I do have an abundance of various grit "Scotch-Brite" pads. I use a smaller then caliber jag (say a .45 jag in a.54 barrel) and poke a slightly smaller then barrel outer diameter by 2-3" strip in the muzzle a few inches. Poke it in, pull it out, poke it in, pull it out (simple minds are easily entertained
). Keep this up for awhile and rotate the barrel slightly each time. I think this method may be a little more idiot proof as well.