Fellows, I think that there is a bit of misunderstanding going on here, in that there are two separate issues that happen very close together. The first is a buildup of powder fouling at the front of the neck part of the chamber. This can be remedied by any means that reaches that part of the chamber with some scrubbing action and solvent. The second issue is hard carbon buildup at the start of the freebore. Hard carbon is so hard that no solvent that I know of will touch it except for possiblyCRL and I have never tried that approach and would not describe it as a gun cleaning product. What is left is something like IOSSO used properly and carefully, no more than is needed, the particulars of this being material for another thread. Getting back to the confusion, calling powder fouling carbon fouling is IMO at the root of this. Particularly since we have something called hard carbon, which is probably metamorphosed powder fouling, but very different when it comes to what is needed to remove it.