NOT KNOWN FACTS ABOUT BCM LOWER RECEIVER

bcn complete lowerLooked it over so many times and might't find the blem. Everytime I do think I uncover anything off, it is just oil smudges. Most effective guess at this time is scuffs on castle nut, or the two little silver places while in the flare from the magwell. 1mm dots at most. BCM QC would not mess all around It appears.This assembly inc