The only problem with JB is, it works mechanically so it removes not only copper but steel. I'd like to hear others' take on it, but personally I'm reluctant to use it in my barrels repeatedly, long-term. Whereas I don't worry about a product like Wipeout that removes copper chemically, without affecting the steel.
I have a couple copper fouling mutha' of 243's that get the JB treatment about once a year.
But like you, I use it sparingly.
Casey
