The upper receiver arrived along with Wilson Combat’s new Whisper suppressor. The bolt was removed and placed in a Colt bolt carrier to facilitate select-fire operation. They were mated to my proven M16 lower with a few extras. It was tested both in semi-auto, select-fire, and even with complete magazines on full-auto. It looks like this system works fantastically for CQB work. Take a look at my short video of it in operation, and take a closer look at my full review coming up in Special Weapons for Military and Police. The results may surprise you—they certainly surprised me!