Some of the types of failures I used to observe with the M-16A1 were definnately operator induced.
NOTICE I WROTE M-16A1 AND NOT M-16A2, A3, or M4 or commercial AR 15 semi sporter whatever.
NCO's wanting to see no junk in lowers encouraged individual troopers to take apart their lower by removing the hammer and trigger and associated pins and springs. This was not on the operator level in the early TMs. It became a sort of "Catch-22" (hey read the book) if one followed the manual it was nearly impossible with the tools available in the barracks or field to pass a weapons inspection, or if one did the break down and was discovered one risked an Article -15 and statement of charges. Further it was possible to loose parts when doing this. The same was true of the bolt as early on removing the extractor and its pin and spring were also not user level.
When parts from those areas were lost they often got imaginatively replaced. Fortnately if in garrison these modifications were usually caught, but in the field (some of us actually lived outside with the M-16A1 and miles away from a unit arms room for weeks on end). Match sticks and pipe cleaners were often pressed into duty until they failed and caused problems that realy did get someone's attention.
Parts in operator maintance areas also got lost and replaced, by far the most common was the firing pin retaining pin. Both a modified match stick and a short section of pipe cleaner some times actually worked a few times before the firing pin stayed behind when the bolt carrier group went forward. Those were a bear to recover. See much of that on civiliam ranges with rifles brought out for the weekend? How about on rifles in units that went out of a day or so at a time?
You did see that sort of thing on rifled that as I said were outside and in use for weeks.
Since I am talking about the M-16A1 and not later models lets talk about the full auto disconector. Some folks in an effort to keep team leader, squad leader, Platoon Sargent, Platoon leader and armorer happy ( all folks that might otherwise see a speck of grunge some where along the arc of the leg of that part or amongst its spring coils removed this part. Do you know off the top of your head how many loops that spring is supposed to have when reassembles or even that it slightly unwound on disassembly? What effect was experienced by putting it back together wrong?
If the rifle was put on "AUTO" and fired it fired one shot. You see the hammer followed the bolt home with the second round and was not available to fall when normally because it did not catch on the bottom edge of the part until it was released by the bolt carrier striking the top of the part. Doing an immediate action drill gave a grand total of one shot and repeat. This meant with eighteen rounds in an old 20 rounder one actually had a nine shot straight pull rifle unless they figured out what was going on and switched to "SEMI"
Keep in mind that one in four Infantry Squad members were designated Auto riflemen and expect to provide 2 to 3 round bursts when engaged. It was amazing how fast those crappy metal clothespin bipods got lost. Their best use was for opening old non twist drink bottles, which could it self bugger them up, but at least discouraged using the magazines for the same. Further at night "Riflemen" and M-203 armed "Grenadiers" were encouraged to us "AUTO". The comic book mentioned earlier ( I still have mine and love the Will Eisner art) encourage switching to "Auto" to gain local fire superiority when caught in an ambush. This meant all M-16A1 users were in danger of having a non functional rifle if they messed with the auto disconector, yet out of fear of having a "dirty rifle" many folks messed with that assembly.
Yes, the comic book and TM explained that white glove type inspections were a no-no, but imagine pissing off your Junior and Senior rater for you Enlist Evaluation Report by not having the pristine rifle they expect. Real world moment.
Say ever wonder why there is a drain hole in the screw that holds your butt stock to the recoil spring tube? Guess what? Firing those robust M-16A1s, and I guess since the screw is still in use about any AR-15, after immersion can result in water in that tube (which can not be compressed) needing to go some where. Sometimes if that hole is well and truly clogged it goes out the back of the tube.....after removing the tail of the tube. Yes nothing like seeing an M-16A1 with no butt stock over the recoil spring tube and the recoil spring dangling from the black cylinder until eventually the buffer and spring fall out.
Make you think of the M-16A1 as a truly robust system that does!
Ever find a little spot of mud in your under shirt after firing the AR15? That is were wet dirt or mud was forced out that drain hole while you were shooting. You say you never have......maybe you are not living with an AR ourside day in and day out and doing those afore mentioned three second rushed a lot on your week end range trips. After the Army started using those airgun things to give us our vacinations with, I worried a bit about the lube, water, and crud that was being directed at my oh so not robust skin on my shoulder.
Say, anyone know why the Probus style wire cutter bayonets have a scallop to use as a bottle opener, why to dis courage the use of those oh so sturdy and non fragile aluminum AR magazines as bottle openers.
Ever tried to recover an AR that had an extractor come loose in use? (remember those pipe cleaners ad match sticks) Some times you can shake, bounce, pry and cure it into a positing where it does not block the rotation of the bolt......sometimes depot maintence gets a complete upper to try and salvage parts from. Of course some times the extractor with unauthorized pin takes off to parts un know out the ejection port. Ever seen a spent case thougholy wedged into a chamber by the attempt of a rifle to load the next shot and that loaded round being hammer repeatedly point first into its base while Joe Snuffy tried to do immediate action drill with a rifle that is not ejecting at all?
Hmmm, I have read the many posting about that useless appendage on the right side of the upper, the Bolt Forward Assist. I wonder why the US Army (who has been lauded by some here for making the AR the longest running rifle system in the US military) felt it necessary in the first place and still has them on rifles and carbines being made today? I have seen lots of folks use them and I have used them when the bolt carrier failed to go fully forward in live fire. We used them everytime we loaded a first magazine going on patrol AND occasionally gave them a tap just to be sure. You really did not want to hear the hammer smacking the inside of the bolt carrier and not quite reaching the firing pin because the bolt carrier was fully closed. This how ever added more parts folks could mess with or mess up.
Those old triangular hand guards did break a lot, it was one thig our armorers had plenty of. Those neato cooling holes were actually semi circular cut outs one each half of the handguards. The "teeth" between holes got broken with great regularity and when three teeth were broken on half a handguard it had to be replaced. Mean while a single broken "Tooth" might have an edge sharp enough to cut fingers thumbs and palms using the handguards in a normal manner.
Maybe I just don't have enough experience but I never witnessed and M-14 or M-1 having the front swing swivel fail an a rifle sing down I a long arc and damage the front sights, or even just fall of in the field and result in some one tripped by his own rifle. Actually saw the first twice and the later once with the M-16A1. Darn but those made me glad to have a sturdy rifle!
I actually liked the 3 prong flash suppressor on the XM-16 series before the bird cage supressors, that said I saw individual fingers on those bent or even missing. Of course the were terribly miss used when troops used them to break the steel packing bands found on things like C-rat crates. Two guys would slide the 3 prong over the strap from different directions and twist. Not some thing I think Gene Stoner and Burt Miller had planned on them using them for. Fortunatley the bird cage prevented Joe Snuffy and Gomer from using this method of breaking steel packing bands........so of course they came up with another way to do the task. They would stick the barrel itself under the strap from two different directions and use them like pribars. Direct quote time, "Naw ,that couldn't have nothing to do with my rifle loosing zero in one week, that barrel is steel so someone must have messed with my sights." Obviously Europe is infested with sight turning elves that Tolkien failed to mention in any of his books.
Last but not least lets talk about those wonderful gas rings on the tail of the bolt itself. I have been told by a well know carbine guru that those things make no difference. At one of his classed I attended a father and son where shooting older 16 inch CAR stocked guns and having failures to feed every four or five rounds. The instructor doused the carbines in oil, changed magazines and wailed away at the Forward assist and got no better. When this family group stopped for a break to reload magazines I wandered over and asked to examine their rifles. One had two rings up front perfectly aligned and the third ring opening with in 30 degrees of the first. The second had the front ring about ten degress from the second and the third aligned with the second. Using my handy SAK plastic tooth pick I rotated all these rings' openings 120 degress apart (just as it says in the manual) And Viola' the rifles functions MUCH better though each still suffered a failure or two with each 30 round magazine. The big name instructor was convinced that my quick fix on the gas rings was not what made the difference but was at a loss to say what other than his lubing (which had made no difference before) ws to blame for the improvement. I saw this happen in service rifles, fixed them and so knew it worked and opening placement on those rings does matter, but have been told by many since it does not have any thing to do with rifle functioning.
Not one problem I have written about have I not personally seen happen or seen the non functional rifle after it happened.
Nothing can convince me that the XM-16 series, M-16 or M-16A1 or early SP1 rifles were as robust as the M-1 and M-14 rifles.
-kBob