It works VERY well for me and has done so for all the various powders I've used in my rifles. The technique that's worked best for me is wrapping a patch around a brush and soak the patch with the Flitz, then several full length strokes in the bore (maybe up to 10 strokes) and copper and carbon are gone. Sometimes that doesn't get all the carbon ring out so easily after a heavy build up so I take a the heavy duty blue iosso nylon brush with iosso to more easily takes care of that.What's you folks opinion on Flitz Bore cleaner for removing copper. I already use Iosso and JB. Just wondered if getting some Flitz would be worthwhile.