I shoot a 300WM Sendero, factory barrel (can't wait to burn that sucker out...). I've always had some fouling issues, but I typically shoot ten or less shots per range session so it was manageable as I just foamed the barrel afterwards. Lately I've been trying to empty some new cases to reload them for an upcoming elk hunt so I've been getting a lot more trigger time than usual -- more shots per session and more sessions. I've found that if I do not rigorously clean the barrel every ten shots or so, I only get 3-5 good shots in the next time before accuracy goes. By rigorous cleaning I mean half dozen passes with Butch's Bore Shine alternating with bronze brush passes, a bore foam, and then a dozen more Butch's passes alternating with bronze brush passes. Typically I get a bunch of carbon out, followed by more copper with additional carbon. The last time, even this was not enough. Last night I'd had it and after failing to ever get clean patches out (and not just the copper residue from the brush, but still carbon even after this long procedure) I plugged the barrel and filled it with copper solvent for 20min. This seemed to solve it, but this is making shooting a bigger pain than my muzzleloader. Is this normal with these factory barrels? Can I expect better when I toast this one and get a custom barrel installed?