First, I use a good solvent like Montana Extreme to get the copper and a lot of the carbon fouling out. Then, about every 250-500 rounds I follow the solvent with a couple patches loaded with JB. Then I follow that up with Kroil.
The JB gets out carbon that most solvents have trouble with. But, the real reason to use JB is to polish the fire cracking in the throat. I think barrels shoot better for longer when you keep the fire cracking under control.
