Well, luckily I had you guys to tell me the one problem that WOULD have raised it's ugly head had I not been offhandidly warned. Carbon buildup. But I had my properly sized, handy dandy, do it yourself drill bit at the ready to remove that ugly mess after 10 or so shots. Other than that, my TC .50 cal barrel loves the stuff. I got increased velocity, hell of a lot easier cleanup, and much easier reloading. Not to mention it's a LOT easier to see through the "smoke cloud". Like Pete said, it's vaguely disguised smokeless powder.