It doesn't have to be perfect, unless you are of the type that just can't stand seeing the burn/scorch rings on the front of the cylinder. Myself, I just take an old toothbrush, dip in some solvent (Hoppes #9 for me) and scrub off the carbon and crud and call it good. I don't try to worry about scrubbing off the burn marks there or on the front of the cylinder. As long as the crud is off, it's good.
If, however, you are of they type that insists on removing the burn marks, the above-mentioned Lead Away cloth works wonders. Using the "shoe-shine" method on the top of the barrel stub/forcing cone works well. It's just that, myself, I don't see the need. The burn marks will be back with the first shot you fire out of the gun and you'll need to scrub it all over again. Remove the crud and call it good. Think of the burn marks as proof that you actually shoot your guns, instead of just looking at them. That's how I rationalize it, anyway.
Bub