# 1965 - 1967. Field reports from Vietnam began to look much more pessimistic. M16 rifles, issued to US troops in the Vietnam, severely jammed in combat, resulting in numerous casualties. There were some causes for malfunction. First of all, during the introduction of the new rifle and its ammunition into the service, US Army replaced originally specified Dupont IMR powder with standard ball powder, used in 7.62x51mm NATO ammunition. The ball powder produced much more fouling, that quickly jammed the actions of the M16 unless the gun was cleared well and often. This pitifully combined with the fact that the initial M16 rifles were promoted by the Colt as "low maintenance", so, for the sake of economy, no cleaning supplies were procured for new M16 rifles, and no weapon care training was conducted fro the troops. As a result, soldiers did not knew how to clean their rifles, and had no provisions for cleaning, and thing soon turned bad. To add the trouble, the ball powders also had a different pressure curve, so they produced higher pressures at the gas port, giving the rise to the rate of fire, and, thus, decreasing accuracy and increasing parts wear.
# 1967 - 1970. The deficiencies discovered in previous years began do dissolve. 5.56mm ammunition was now loaded using different powders that produce much less residue in the gun action. The barrel, chamber and bolt of the rifles were chrome-lined to improve corrosion resistance. Cleaning kits were procured and issued to troops, and a special training programs were developed and conducted ever since. Earliest cleaning kits could be carried separate from rifle only, but since circa 1970 all M16A1 rifles were manufactured with the containment cavity in the buttstock, that held the cleaning kit. At the same time (circa 1970) the new 30 rounds magazines were introduced into service instead of the original 20 rounds ones, to equal Soviet and Chinese AK-47 assault rifles, which had 30-rounds magazines from the very beginning.
... ...
At the present time almost all initial flaws of the M16 are bugged out, and it is considered among the best assault rifles in the world. While its reliability in the harsh conditions cannot match reliability of its main rival, the Kalashnikov AK-47 and AK-74, it is still a quite reliable rifle, especially when well maintained. It is also comfortable to fire and quite accurate.