i'm a long retired Army M/Sgt. and disabled RVN vet. The history of the M16 rifle is a very long one. Yep, it has been a very good battle rifle for the past 40+ years. The M16 has not always been a good battle rifle. In the beginning it was a sorry piece of work that was fed some sorry ammo. The M16 was accepted for use based on the use of grained powder. Then the US Army decided to use ball powder. That was a sorry decision.
My brother was a Sgt. in C Co. 2nd Bn, 7th Cav. He went to Viet Nam with the unit in 1965. Still have the letter he wrote asking me to send him a cleaning rod, bore brush and patches: Yep, the Army issued the troops M16 rifles without cleaning kits. Sec Def McNamara, Colt and Stoner claimed that the gun was "self cleaning" and the troops did not need cleaning kits.
That ball powder increased the cyclic rate of the M16 and this resulted in more wear on the weapon. That powder was also very dirty. The gun did not initially have a chrome plated chamber and this lead to rust and failures to extract the fired case. The micro managing McNamara said: "If the gun needed a chrome plated chamber, Stoner would have made it that way."
The US Army insisted that their M16 have a forward assist. The USAF guns did not have that feature.
My brother was killed at Ia Drang Valley on 17 November, 1965. One of these days i will have the great pleasure of 9issing on McNamara's grave.
http://www.bravocompanyusa.com/articles.asp?id=125
The Army began to immediately issue the XM16E1 (re-named M16 on its adoption) to infantry units, and the rifle was initially delivered without adequate cleaning supplies or kit. Moreover, the Army's inability to deliver 5.56mm ammunition meeting quantity and velocity specifications led to a change in powder specification for the 5.56mm cartridge. Unfortunately, the change was made without testing the modified ammunition in the rifle under service conditions. The newly-specified 5.56 ammunition increased the cyclic rate of fire, increasing wear on parts, and the new gunpowder's burning characteristics increased fouling in the M16 rifle.
When the XM16E1 reached Vietnam with U.S. troops in 1966, reports of jamming and malfunctions in combat immediately began to surface. Although the M14 had a chrome-lined barrel and chamber to resist corrosion in combat conditions (a danger learned from WWII Pacific theatre combat experience), the M16/XM16E1 had no chrome-lined bore or chamber.
Several documented accounts of troops killed by enemy fire with jammed rifles broken-down for cleaning eventually brought a Congressional investigation. Later investigations also cast doubt on the veracity of the original 1962 reports of the alleged stopping effectiveness of the 5.56mm bullet, as well as criticism of inadequate penetration (in comparison to the Soviet 7.62mm x 39mm round) when firing at enemy personnel through light cover.