The etching with ammonia based cleaners only occurs if you let it dry out on the metal, if kept wet there should be no etching. On really problem barrels I would plug the muzzle and fill the barrel with the copper remover, it can stay like this muzzle down over night with an oily patch in the chamber.
Lately except when applying DBC I have not needed anything more aggressive than JB bore cleaner with any good solvent. For routine cleaning I will be going with Wipe Out more and more as I use up the other products. With the de-coppering gun powders the need for the ammonia based products is practically nil.
