I have a aero precision M4E1 Pro rifle in Kodiak Brown. I swapped the barrel for a Larue Tactical Predatar 16” barrel. This pro rifle has the new full ambi lower and mod 4 rail. There are some spots in the anodizing that have some black spots that I have shown in pictures. Looking for $1300obo text for faster response 9zero 3 two 45 three seven 57