Don,t worry about it,people now days are getting out of control about cleaning there guns. Barrels have had copper fouling for years and years before this new cleaner cam out and there was never a problem! you can wear on the rifling by cleaning it to much just as if you were shooting it. Your just fine in leaving it for a few days,Its only with blackpowder is when the need to be cleaned immediatley after shooting. vangunsmith