Last 1 1/2 inches would imply it is from whatever powder was used in it and not cleaned properly.as suggested before, i would JB and oil the barrel and follow the swabbing between shots and cleaning regiment that SABOTLOADER suggested.if you end up using BH209, throw the swabbing out the window and buy a good center fire barrel cleaner.Hoppes.birchwood Casey bore scrubber ETC.That darn Jon sold me on the bore scrubber, works excellent and even smells good to boot Ray