I recently just finished building my first AR-15. I bought a Rock River Arms completed lower receiver, and attached a complete, 18" .223 wylde upper receiver with a included BCG and CH. I have shot 150 rounds through it so far. ZERO HANG UPS shot beautifully. when I broke it down however, I noticed what seemed to me to be excessive wear on the upper's rail that the BCG sits on. The Wear is only on one side and appears to be uneven and choppy. Ive attach pictures. Is this normal? Will it throw some shavings just at the start? I Bought a brand new Sig Sauer 1911 that did that but only because of the tight tolerances and also i read that that was a normal occurrence.