I was only shooting sabots out of the one I had so it could be nothing else. After that first shooting session I pulled the plug and cleaned the gun and the barrel was awful looking. From the breech running about halfway up the barrel it looked like the metal was flaking off. When I bore brushed it I got a bunch of shiny silver flakes. I eventually got all of them out between shooting and cleaning but it was a minor annoyance. I don't think they do that good a job plating them. Maybe just dipping the barrel and plating it inside and out is the cheapest way of doing it.