KG-1 Carbon Remover and KG-12 Copper Remover, and Boretech C4 Carbon Remover all came out after the article, IIRC, so they didn't get mention.
The two drawbacks to Slip 2000 are that it can gradually etch Parkerizing over a period of hours (guess how I know) and it can induce corrosion in non-stainless steels if it's left to dry out on them. However, when I have left very thick, hard, aged carbon cake in it for several hours, it really did penetrate and soften it to the point it could be removed with brushes. The Boretech C4 Carbon remover (and their other cleaners) have corrosion inhibitors and are harmless to steels even if left in the bore indefinitely. I suspect, since it is mainly a surfactant mixture, that, like KG-1, it can be reused indefinitely. The KG-1 is pH neutral, so it won't induce corrosion, but I don't know if it has corrosion inhibitors specifically.
Neither C4 nor KG-1 are as aggressive as Slip 2000, but if you are patient, they work well. If you are really, really patient, Gunzilla will dissolve carbon over time, combining with it to form a tar-like sludge that flows to the bottom of whatever it's in, eliminating all patches and elbow grease. But you may be talking a week or more for all that to happen. It mainly seems to depend on how old and hard the carbon is. If you use Gunzilla's pump sprayer right at the range to get it into the still-warm carbon, you'd be impressed by how much comes out with one patch. Sometimes all of it if the bore is in smooth condition. But the C4 and KG-1 will also have their efforts enhanced by a spritz at the range.
Do keep in mind that none of those products are copper removers, though the penetrating effect and oxidation will remove some anyway over enough time.
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