I remember the original Barnes "X" bullet fouling so bad it prompted Barnes to introduce their own line of copper fouling remover. Industrial grade ammonia worked too, just use in a very well ventilated area, don't leave it in the bore too long and don't get it on the finish of the firearm if you had any interest in keeping said finish! Only tried the industrial stuff a couple times. I've been using the Barnes bullet since the originals and now, pretty much, use them exclusively in everything from 223 Rem to 338 WM, coyotes to moose.
