While cleaning my AR after yet another great trip to the range this weekend I noticed something that got my attention. The parkerizing, or whatever finish, on the face of the lower locking lugs is showing some wear while the others still appear new. My only ideas are that either something is out of whack, or that the lower locking lugs are receiving a little more wear than the others from stripping a fresh round from the magazine. For reference, I bought the rifle new and have put about 1200 rounds through it. It has never failed to feed, fire, or eject.

Thanks in advance.