Can I mount a military contract 16" M4 upper on my Colt MT6731?
Will the Bolt, Carrier, & charging handle from the MT6731 fit & funtion properly in the M4 upper without changing the headspacing or anything??
I have the MT6731 upper set up for varminting (Scoped w/no iron sights front or rear) & would like to be able to put a "Entry" style upper on it useing the same Bolt, Carrier & Charging Handle if possible!!!