GI John TV features the FN Herstal M16A4 "The Baghdad Blaster" in this video... "The M16A4 was designed for one principal, which is modularity and more flexibility with more attachments to further increase the lethality of this platform. So far, it's served many decades and is still performing very well in all branches, especially the Marines. The M16A4 is a direct impingement gas system with a 20-inch 5.56 1:7 Twist CHF barrel, providing the full potential power of the 5.56 round."