FN M16A4

The FN® M16A4 is an M16A2 with a removable handle and full-length quad picatinny rail. The M16A2 weapon system was developed at the request of the United States Marine Corps to improve on the M16A1 and went into large scale production by 1987. Improvements included a thicker barrel in front of the front sight, modified flash suppressor (closed on bottom), new polymer buttstock (lighter and stronger, faster barrel twist (from 1:12 to 1:7), and spent case deflector for left-hand users.

The M16A4 is chambered to fire the 5.56x45mm (.223) NATO cartridge. It is a select fire rifle having semi-automatic and three-round-burst fire capabilities. Cartridges are magazine fed, and firing is achieved via a direct impingement gas operating system.