For me - Break Free and Scotch Brite pads. If the carbon is really heavy then I use my cordless drill. I cut the pads into strips about 3/4 inches wide and about two or three inches long and place it over a 20 or 28 ga bronze brush to clean a 12 ga choke tube. It'll clean up the worst carbon build up in just a few seconds. JPM
pick up some slip 2000 ewp oil. Clean the barrel with any good cleaning stuff. The 725 cleaner by slip is good, kroil is good, Remoil is OK. Hoppes is good. anyway, the slip oil coating, after the cleaning, will remove the "carbon" from the chokes, except it probably isn't carbon. It is most likely burned on plastic fouling from the plastic wads that partially melt going out of the choke tube. After a few times of treatment with the EWL, the plastic fouling comes off in one burnt plastic sheet with just 1 or 2 mops run through the bore. Easy Peasy. Try it, you will like it.
I like Gunzilla. I have never had a problem with it damaging my gunstocks as someone mentioned in another post. In fact, on their own website it states "Gunzilla can be used to clean wood and plastic stocks; simply wipe them completely dry after cleaning."
I use a 10 ga. brush on a cordless drill. I don't replace it very often since I realized the cleaning rod is far from balanced and as such wobbles sufficiently. It is now down to about a 20 ga. diameter. For over 30 years I've been satisfied with Hoppes #9, soft pipe cleaners, and a plastic pic and patch to get into the tight spots.
Top Engine Cleaner 105002. Is very good stuff and work well when I work for GM back in the 70's.
So did water. You just spray a mist over the carb and hold the throttle open. The carbon was gone.
Today if I have a carbon build up choke I just up it in hot water for a minuet and run a brass brush in the choke. The choke is clean.
I would water the cheapest why to go.