When you are shooting 50g-70g of powder or more and you have a bore scope, getting down to bare metal in your cleaning is a humbling education. The copper had long gone by the time I was concentrating on the powder fouling.
I hope you have or get a Teslong bore scope. I have one at the lathe to inspect chambers before I pull the barrel out of the chuck, and another at the cleaning station, good insurance...keeps you humble.
I grade abrasives in how fast they cut carbon, choosing appropriately for the job needed, not overkill just to be in a hurry.
Jb is the least
Iosso bore cleaner
JB (red) Bore bright
Turro Clean is the most aggressive
The old Rem Clean in the yellow container is the most aggressive I have ever used, and it would round the lands.
Removing hard carbon, good bronze bristle brushes, best use in 60 strokes, retire them at 100
Iosso and Montana Extreme plastic brushes are used to focus on carbon buildup in the barrel. The appropriate solution is determined by the carbon buildup/surface finish of the barrel.
Winding 0000 Bronze wool in a used bronze bristle brush, scrubbing with Free All is a VERY minimal way to attack small build-ups in carbon. Letting a Barrel soak with the Free All also helps, applied with a saturated Wool mop.
Very minimal efforts are often needed when powder charges are 40g or less, using good, fresh bronze bristle brushes.
When guys talk about their success with this or that method, you have no context to see if it applies to your particular situation. A guy shooting a 223,6PPC, or a 6 BR does not live in the same world as a guy shooting a 7 PRC. The same thing would apply to different internal bore smoothness issues. A guy who cleans every 20 rounds may have a completely different experience with the same product when only cleaning every 40 rounds, where carbon is starting to build up.
May God have mercy on anyone cleaning with Wipe Out using patches ONLY! I bought a used Broughton 6 PPC barrel for my Panda. The Broughton is carbon fouled badly. I have been soaking with Free All and scrubbing with bronze bristle brushes, and the throat looks new. The gunsmith told me that the barrel was shot out, and I got it for $75. The barrel is nowhere near shot out. After I measured it with a Grizzly Rod and reamer bushings, the throat dia is the same dia as the muzzle dia. The guy cleaned with patches only, wanting to be too gentle on the barrel.
Life is too short to deal with Rough barrels. Considering the cost of cleaning solutions, patches, and brushes, it is wise to spend that money in advance on a barrel maker that inspects his product before leaving the factory, including a bore with a very good internal finish. Insist that your gunsmith inspect the bore prior to chambering; this is critical.
Sorry for the Rant!