Originally Posted by SSGN_Doc
After the hot soapy water you need to use a water dispersing oil like WD-40. Then clean that out and put a protective oil in there to provide a barrier from the air.
The advantage of using boiling water in the cleaning process for corrosive ammo is that the water evaporates almost instantly. It also leaves the barrel scorthcing hot, which I believe helps with the chemical action of the Hoppes, or whatever other cleaner you use. With normal cleaning after the water, there will be no moisture in the bore; no water, no NEW rust.
The other thing to remember is that most of these rifles have had the bores worn or damaged to some degree. There are pores, resulting from previous corrosive damage, that are full of all kinds of crud that will soil patches dang near forever.
I have tried and tried and tried to get clean patches out of some of my Mosins and have come to the conclusion that it just ain't gonna happen. It doesn't appear to affect the functionally or accuracy of the rifle, so I have learned to quit obsessing over it.