Lots of war stories about trading for an AK don't include the fact that after a few firefights, you knew the distinctive sound and directed fire at it. In dense cover, there's no way to tell who is carrying it.
I put it with the "firing pin as a nail" BS.
It's archived at arfcom, and their server won't allow links. A post up this year discussed all the powder and chrome issues, along with the magazine changes, which were significant. Lots of comparisons are made to the AK, look at the robust design, then check out theGI M16 mag. You can drop it fully loaded on the feed lips and it will be screwed up good. FTF will start happening because of the light sheet metal lips getting bent, unlike the machined steel feed lips on AK mags.
There is another element frequently left out. Colt was making M16's just fine, and up to 1967 they ran OK. They were in low production rate mode, and the contracts were small, allowing a lot of fitting to get the parts right. It's NOT like it is today, weapons makers got good tolerances, just not as tight as some would like. Sometimes they needed a lick or too to get right, and they got it. There were glowing reports of the early contract rifles going quite well.
As an aside, that aluminum receiver and composite furniture added a lot to the "don't need to clean it" concept. On the outside, the only parts that were steel were the sights and exposed barrel. ALL the rest didn't rust or corrode. You really DON'T need to clean it - like a wood stock and steel M1 or M14. Huge difference.
Once the ramp up in production was going full song, Colt was putting out 4 times the production. There's only one way to do that, buy outside parts, and hire new workers. Quality suffered (just like it did in the '80s,) and inspecting each incoming part from an outside supplier apparently didn't happen in a thorough manner, if at all.
If you've worked a production line and understand tolerance stacks, you know this, but in the last 30 years, those jobs have all gone overseas. It's not part of the American labor experience any more.
One supplier of barrels got the chambers too tight. The M16's shipped. They jammed, especially during a infamous firefight in which the soldiers, with almost no training, no cleaning supplies, and a large number of draftees, had problems.
I say draftees because when the Army says you have to do something, it's part of human nature to resist. Even volunteers, and non-firearms enthusiasts are a larger part of draftees than volunteer in the day. And since you were literally kidnapped and forced to be there largely against your will, don't expect them to fully understand and cooperate with mundane grundgy tasks they don't want to do.
Subsequent to that action, it was discovered the chambers in those weapons were tight, and armorer action teams put in country with truckloads of new M16's with inspected chambers. Every unit was hunted down, some even in contact with the enemy, according to the participant's eyewitness accounts. Chambers were gauged, no go's set aside, and new weapons issued on the spot. If you were lined up waiting, you caught on fast, and some created expedient damage to get a new rifle, deserved or not.
Once you sort out the stories, as I have even before I graduated high school in 1971, you get the idea that firearms knowledgeable soldiers had little problem. They cleaned them however, as I did, and had to, without sufficient supplies. If your issue T-shirts are stained at the tail, and smell like lubricant, you know. As for the others, I seriously doubt they would have done much better had supplies and training been given to them. They simply refused to do what they were told, and that is another reason the all volunteer army works better.
Were they told wrong? No, not always, and the easy excuse to blame nameless higher ups for a conspiracy to make millions doesn't change the fact that lots of other units with competent commanders and NCO's didn't have major problems. A lot of it was due to a mindset that create some bad situations, and never should have happened. That is a continuing problem in the military, and it will never go away, regardless of the effort to educate and train every soldier. It's directly related to being human, and humans are not perfect.
Expecting perfection from organizations of humans is it's own reward.