i never shot a lot in those 35 years,so maybe thats why i never had build -up. all my practice was behind shoulder of buck,ha.but, i do feel ,as you that HOT water will cause RUST.like you say, if not dried right away,oh boy.i bet many are getting rust from this and not bore butter. i know that for fact because i never got rust in 35 years until i used ,HOT WATER.