GETTING MY COLT 20 INCH HBAR UPPER TO WORK

The present-day M16/M4 rifle is developed around the thought of modularity. Most of the BCM® flat leading uppers attribute a USGI style laser etched T-marks to provide addressing for the remounting of tactical extras for example optics, laser sights, etcetera.  This is the new upper receiver group, taken off a full Colt rifle.  Ships in army gra