He should be more worried about that full-auto upper receiver than the scratches inside it.
OP, consider...how many times that charging handle will have been utilized to ensure that weapon is clear or to make bright lights/loud noises, from the moment it's initially assembled, to it's test-firing, to being placed in a box for shipping to a vendor, then perhaps getting handled by that vendor, etc.....? Lots.
What you see is completely ordinary. It's now up to you to help those little polished areas get bigger.
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Some posts were deleted, because none of us came fast-roping down mama's umbilical cord knowing ANY of this stuff. To those affected: Get it together. Pretty-please.
Lastly...on the offhand chance that it's not known..., full-auto requires a particular lower configuration, and since this thread's about an upper, we can just let that line of inquiry drop as being irrelevant.
I think we can out this to rest now.