I use a combo of CLP, Shooters Choice bore cleaner and a good bore brush such as Outers Phosphor Bronze wire brush.
I apply(saturate) the S.C. bore cleaner to the brush and trombone action the barrel atleast 10 times to loosen up the fouling, then a patch w/CLP. I keep doing this until clean. This also works very well with stubborn leading from shooting slugs and you can switch the SC bore cleaner with SC lead remover.
Good luck