Shooting will "smooth" out a new barrel. Most all but the very best custom bbls. will have very small deviations and microscopic crevices that can be detected with a good bore scope. copper fouling will "fill" up those crevices to a smoother plane. that's why shooters today don't clean their bbls. as often as they once did. I never use a wire brush on mine, only wet patches. I don't want to "dig" that filler out of those cracks, etc.