The M16A4 was developed by Colt Defense in the Late 1990’s as an upgrade to the M16A2, which had been in service since the 1980’s. The M16A4 is a variant of the M16 rifle from the 1960’s. The M16A4 is a select-fire, gas-operated rifle that fires the 5.56x45mm NATO cartridge. It has a maximum effective range of around 550 meters, and a cyclic rate of fire of around 800 rounds per minute. It is equipped with a 20-inch barrel, a detachable box magazine, and carry handle. With the carry handle detached the M16A4 can be fitted with various optics and sights. This specific example features a backup iron sight by MaTech. The flat top upper receiver is the distinguishing upgraded feature of the M16A4. It was first introduced into service with the United States Marine Corps in the early 2000’s, and has since been adopted by a number of other military organizations around the world. It has been used in combat extensively in the middle eastern theater of operations. Most notably Iraq, and Afghanistan. It has proven reliable in said theaters, although its role in close quarter combat is marginal compared to its carbine counterpart the M4A1.

Identifiable features of the M16A4 are first and foremost the flat top railed upper receiver. These rifles where issued with a detachable A2 style carry handle that were seldom used. These carry handles are often removed since the railed upper receiver allows for the use of optics such as the Trijicon ACOG. This was the main purpose for switching to the M16A4 from the M16A2, to allow for the use of low power battle optics to extend the effective range of all soldiers, and marines. In addition to the flat top railed upper receiver, the M16A4 also was usually issued with a two piece drop in quad rail handguard. These were instrumental in the implementation of white lights, foregrips, and infrared laser designators on the rifle.

he M16A4 shares many similarities with the M16A2, such as the same A2 buttstock, A2 grip, and A2 front sight block. Lower receiver parts such as the safety, magazine release button, and bolt catch operate the same as well. They are both Colt Manufacturing marked, with property of US government markings as well. The M16A4 marking, and in certain units the Unit Identification QR code plate were the only major markings that differ from the M16A2. It has been issued in all four branches of the United States Military, and has seen service world wide since its adoption.