I've got a 12g barrel that was neglected and I'm having a hard time cleaning the fouling out. I've put several wet patches (Hoppe's) through it and left it over night. I've run a boar snake through it more times than I care to count. I've tried break free. I even put a copper brush on my cordless drill and tried to break it up. Still have a lot of build up in the bottom 1/3rd of the barrel. Is there anything else I can do or is it a lost cause? Is that foaming cleaner worth trying?