I’m kinda like you, if the brush or mop gets that nasty, I trash it. I figure you’d spend as much on cleaning solvents than a new brush would cost. Sure don’t clean patches. they get trashed.
First I ever heard of using brake cleaner on guns, I wouldn’t use it. I cleaned some wrenches with it one time and it eat the chrome off some. I wiped em off too. i’d be scared to spray the stuff on any gun. It would for sure eat the finish off stocks.
Also cleaned the valve cover on a Cummins engine with it one time, it eat the aluminum a bit. made it look bad, worse than it was.
I don’t buy all those name brand oils, Mobil 1 has worked for many years even with full auto fire. sometimes in the summer if I know i’m going to put a couple thousand through a gun in a day or two i’ll use grease. but never store one with it for years on collector guns. found that out the hard way too.
grease dried and got hard and gun wouldn’t function, took a while to get it out of moving parts.