The man I speak of said boiling water.
Ned used iron barrels that needed re-freshing (rifling re-cut) often? Anyone suggest why?
Holland and Holland - the OLD English Gun Making Firm, makers of "best" quality muzzleloading guns, single rifles, single shotguns, double rifles, double shotguns, and bolt actioned modern-type guns as well, wrote my friend in Smithers and told him to NEVER use hot water or boiling water for cleaning his muzzleloading or black powder cartrige shooting rifles and shotguns. They told him he would flash rust the gun's bores and the effects were accumulative - just as we've found out ourselves from friend's guns. These were friends who have not believed our attempts to pass on this knowledge from Holland and Holland.
Will, my friend now gone from us this last winter, had double rifles and double shotguns, ctg. and one 6 bore double 6 bore ball and shot gun made by H&H as well as a number of other British makers of the mid to late 1800's - he always sent a 'new acquisition' to H&H for refurbishing and re-proofing as well as having a new leather and brass bound gun case made for it.
It was their correspondence to him that I read and which methods of cleaning, I have chosen to duplicate myself in all my guns that shoot BP. They were right - cold water dissolves BP fouling - it does this in $20,000 to $60,000 dollar guns just fine and it seems to clean my $500.00 to $3,000.00 guns just fine too. Never rusted a bore since I switched to cold water.
They noted that boiling hot water has a glazing effect on powder fouling buildup on the breech plugs.
Ever wonder why some of us do not need a breech plug scraper and some do?
The Holland and Holland I spoke of above, is NOT the NEW US firm who makes muzzleloader barrels. They are NOT affiliated with each other in any way to the best of my knowledge.