Lime away might do it-never tried it myself. Mike Venturino, blackpowder editor for Shooting Times magazine, usesWindex with vinegar for all his blackpowder cleaning. Got onto it myself about five years ago. In a apray bottle or ona wettedpatch it gets the crud off the scope, the breech plug, receiverand out of the bore. It also works very fast, softening and washing away the crud.