RE: Hot Water...
There are as many opinions on the quality of bore butter and the protection it affords your rifle as there are black powder shooters. For years people have been protecting their rifles with bore butter. The trick is you have to be absolutly certain that there was no moisture trapped in that barrel.
I stopped using bore butter a long time ago and after I have my barrel spotless, I use Birchwood Casey Sheath. Sheath was suggested as a great barrel oil by Triple Se7en. He was right on the money with that one. I have gotten to where I really depend on it to protect my rifles.
Good luck with your bore butter. If you ever need to remove it, again with the boiling water and flushing the rifle bore...