OK, it just got even more confusing. I was thumbing through the 1995-96 edition of Jane's Infantry weapons and they are quite explicit about the M16A3 (Colt AR-15 Model Number 901) being a flatop M16A2 with a full-auto fire pack. They correctly identify the M4A1 (Colt AR-15 Model Number 927) as being a flatop M4 with the full-auto pack. Does anyone have a link to a current TM on the M16 family? Also, does anyone have a link for the Marine Corp article on the M16A4? Curiousity killed the cat and all that.