Despite the marketing hype, these lead removal cloths do contain abrasives and do remove metal. Over time they will alter dimensions. They should be used very sparingly. For me, I see no reason to justify the risk and would NEVER run one down my bores or buy an obviously used revolver that had a clean cylinder face.
Sorry, you can't buy ALL those revolvers with clean cylinder faces--mine are staying here--with their clean, un-ruined surfaces, including forcing cones, after having been subjected to Lead Away cloths for years and years and years---and you get the idea...