Testing the waters on my upper receiver group from my Colt SOCOM M4A1. Everything is factory with exception of the flash hider, which has been replaced with a pinned and welded BCM A2X, since it accommodates a bayonet if added, and maintains NFA barrel length legality. Less than 100 rounds have been fired through it.
NOTE: The FSB was marred at some point to get the taper pins out, so it has been smoothed out on the bottom left side and re-phosphated. It is unnoticeable to the untrained eye, but want to be transparent about it.