Congratulations on your new Beretta!
It'll be fine, as the brush is several orders of hardness softer than the barrel. I suspect that the brush is actually brass as opposed to copper, btw.
Copper build-up from firing can cause accuracy issues, so a good scrubbing to remove it using a metal brush and that Hoppes copper solvent is a recommended practice.
Now, we expect a range report and some pictures. nnnnnn-kay?