The M16 is a gas-operated, 5.56mm, assault rifle in service with the US Armed Forces since 1962, replacing the M14. Designed by Eugene Stoner and developed by ArmaLite as the AR-15, it was modified and manufactured by Colt as the M16 rifle, which first saw combat action in 1963 in the Vietnam War. It is the first US standard-issue rifle built with synthetic materials and aluminum alloys. Despite the novelty in caliber and materials used, this modern rifle did not have an auspicious beginning, for a lot of technical problems arose during its baptism of fire in the jungle of Southeast Asia as many jamming cases were reported from the front line and which cost the lives of soldiers. The jamming was caused by malfunction of the ejection mechanism because the rifle chamber was not chrome-lined and the cartridge powder residue build-up clogged the gun operating system.
The M16 is chambered for the 5.56x45mm NATO cartridge, a smaller and lighter round than the traditional 7.62x51mm one used in the M14 and FN FAL rifles. Although the M16 has a lighter recoil than these two bigger caliber rifles, its stopping power and maximum effective range are inferior. As a result, the US Army special forces and US Navy Seals troops in Afghanistan have resorted to the old M14. The safety-semiautomatic-automatic fire select lever is located on the left hand side of weapon, right above the handgrip, with the ejection port on the right side. The bolt carrier handle is also situated on the left side. The rear sight is contained in the back part of the rifle carrying handle. Being able to use the M203 grenade launcher, this light toy-like infantry weapon has been made in four service versions: M16A1. A2, A3, and A4, with the second one having a 3-round burst mode instead of the fully automatic fire mode of the first variant; it was also manufactured with a stronger and thicker barrel, fitted with new rifling.
Type: assault rifle
Barrel length: 50.8 cm
Weight: 3.26 kg
Muzzle velocity: 948 m/s
Rate of fire: 800 rpm (in automatic mode)
Effective range: 450 m
Feed system: 20-round and 30-round box magazines
M16 Operation and Cycle of Functioning