For quite a while I've been avoiding straight water cleaning of my ML's including shotguns, rifles and handguns. I've used an electronic spray cleaner through the nipple hole and some concoction, usually windex w/o ammonia, alcohol, murphy's oil soap and some slight variations. I know there's some water in each of these ingredients which is what I mean by avoiding "straight water". Cleaning with this mix takes between 8 and 12 patches to get some semblance of clean - or still mostly white patches. That's not including an oiled patch afterwards. This worked fine for years. I think I got the idea from Dutch's method and just stuck to it.
Due to circumstances on some travel adventures, I did not have or could not get all ingredients for cleaning mixture. So, I went back to boiled water pumped up and down through the barrel with the nipples in the water and a patch on a jag in the muzzle. First, I just started doing the shotguns. Then I cleaned some of the rifles this way too. Today I did some shooting and cleaned some rifles and shotguns. One patch pumping the boiling water. One dry patch up and down. One with 91% alcohol as a drying agent and to evaporate remaining moisture. One patch with oil. Just 4 patches total, the 3rd in sequence coming out clean (mostly white).
I haven't seen any rust or issues since I switched back to boiling water. For my guns that have a fixed barrel, one that cannot be easily removed, I am inclined to continue cleaning with the "concoction" because I don't want water all in the stock, and I can control the cleaning mix on the patches better. But other than those few, I think I'm sticking to the water for ease and efficiency. If its clean, lubed and rust free I don't care how it got there.