Just a quick note, you might want to see how high your clorine level is before you clean your black powder gun in the kitchen sink.
A buddy of mine recently reported a rust problem with a muzzle loader that he had shot for years. The gun was cleaned the same way and recently started rusting in the bore. Turns out the water company had upped the clorine level and that seems to be the culprit.
I haven't even given it a thought, I've got well water, but when I was on the rural water system and they had a break in the pipe somewhere they'd dump a ton of clorine in the system to the point it'd make you sick. You could literaly smell the clorine in the water. Main reason I put in a well.
Don't know what you could do to fix it short of using some sort of filter or simply letting the water sit a couple of days or getting a gallon of distilled water.
I normally use a half gallon to clean four or five revolvers with a little Ballistol mixed in, so it doesn't take that much water.
Just thought I'd pass this on,