Many will no doubt disagree, but they have no basis for disagreement per se because I have had a little different experience, in actual practice. In cleaning muzzle loaders with plain water, I often get rust forming too quickly for me to prevent, too soon before I even have any chance to apply gun oil etc. Thus the cleaning session invariably complexifies slightly to ensure that I get all of the many bright red rust spots etc (which prob do not do much harm). Those are what I see on the outside, not what I can't see inside the bore. However, when I clean with Dixie's Black Solve, an inexpensive blue musty concentrate that mixes nicely into a 32 oz spray bottle with water, I get no rust forming and have plenty of time to dry and apply Hoppes #9, gun oil and /or any other gun cleaner / follower /protectant that is preferred. No rust ever appears thereafter as long as I am thorough. When I pull it from storage 6 mo later and run a patch in the bore, no rust appears on the patch. Thus, plain water does not and will not every touch my barrels. I don't care if the stuff is just plain windex or whatever the @#@*! it is, it works. I use the same stuff in cleaning corrosive residue from milsurp rifles. Never a problem. YMMV