COLT 6721 UPPER FOR SALE FOR DUMMIES

 Actually, I wouldn't shoot one.  Time to move on to a whole new rifle.  Get an LMT or HK if you want armed service design and style pistons.    Colt has little interest in aiding you out.  They abandoned that venture before their past bankruptcy.Though staring out an airplane window previous week, I marveled on the multiple thicknesses of ac