Carbon cleaning

[Xringshooter]

Most any bore cleaner will do what you want. Carbon build up on a standard handgun isn't really a major problem. Typically it is lead build up (if shooting non jacketed bullets) or copper fouling (shooting jacketed bullets), but copper fouling doesn't normally affect a handgun barrel like it does a rifle barrel. However, if you are talking about an AR pistol, then you do have to worry about the carbon build up and you take care of that just like any AR.

Now, if you are talking about the black marks on the front of a revolver cylinder, you can remove that with a standard cleaner and lots of scrubbing, or you can use a "lead away" cloth (Flitz is one brand, IIRC Birchwood Casey and others make them also). If you use it on a blued gun BE VERY CAREFUL, it will remove the bluing if you get a little careless where you are cleaning. You can also cut a small patch of it and use it in conjunction with your bore brush when cleaning the bore.

[Gunsnwater]

Never use those polishing cloths on blued guns. They are abrasive. Don't worry about carbon on cylinder faces. More damage can result from scrubbing and it just returns.