Ive never used the hot/boiling water method...
Id imaging you'd have to have the barrel vertical & plug the barrel & repeat a few times to heat the barrel sufficiently...?
I can forsee me pouring boiling water over my feet & being left a much bigger mess to clean up...
When i used to shoot that rifle i mentioned earlier in this thread, i would get the cleaning gear ready right before the last group & get stuck in to the copper as soon as those shots were fired & the barrel was hot.
Then id saturate the bore & plug with it with a patch each end for the trip home....it made for much lighter & easier cleaning...!!
The man who knows everything, doesnt really know everything...he's just stopped learning...