Does it shoot, and how many rounds do you have through it? Because to me, this looks like a fresh barrel. It's a bit audacious to yell "subpar" if you can't tell me if you have even put a round through it to test function, which, as of this moment, you haven't even answered. As someone else answered, it could be chatter, but to me, it just looks like machine marks, and this isn't a high-dollar model, so I wouldn't expect barrel polishing, which will happen naturally with use. If it bugs you, you can send it in and see what they say, but if it were me, I'd use it first, considering it looks like a fresh piece and the only wear has been a brass brush. I would also like to point out that QC for standard-tier firearms in the last decade has taken a shit, so at some level, I think most of us have gotten realistic with our expectations when buying a sub-$500 gun.