You're right about that bigcountry...................... especially when shooting Mil-Surplus ammo like I was the other day. That Aussie ammo shoots real nice, but is DIRTY!!!!
I'm pretty anal about my gun cleaning, so I know I got it down to the metal. While cleaning the carbon, I test for copper every so many passes thru the bore to make sure I didn't uncover a Copper mine that had been previously buried.
Typically, I break out the J-Bs a couple times a year to make sure on all my firearms - or if things kind of suddenly change for no apparent cause.