There's no way whatsoever that a bore snake scratched a glock barrel. To even think so is crazy in my opinion. I run a bore snake down shotgun barrel and it always "looks" like it has scratches. That's because the bronze bristles do scratch away at the layer of carbon, fouling and crud in the barrel. Once I do a real cleaning, the bore sparkles like new without a "scratch" to be seen. If the barrel is really scratched, it was done with something other than a bore snake.