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I liked it.
But I liked the M60 better...

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Really? What did you like about it? The spare barrel with attached bipod for extra weight or wiring parts on,etc.? Always seemed like a poor design for a (somewhat) modern MG.

The 60's we were issued in the 80's were absolutely hated by every gunner I knew.

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I carried one while in. Hated the stupid three round burst function. Semi auto is generally what you want to be using, but in that rare instance where full auto becomes necessary, you don't want to be resetting the trigger every three rounds.

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3 round burst is dumb. An optic on top of the carry handle was odd and too high. Never had an A4, I feel it would have been much better for optic mounting. The M4A1 is my favorite. Full auto if needed, ACOG, adj. stock. Last unit we had MagPul CTR and K2 grips with the Knights RIS Kit.

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S/N 7014693

No idea how I still remember that.

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I was USMS Infantry when we transitioned from A1 to A2.  I loved the A2 still do.

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Look, I was there; there were better weapons on the world market, in a lot of respects besides the ergonomics. I owned a Valmet M76 in 5.56mm that was a damn tack driver out past what I could do with my issue Colt M16A2. It had a shorter barrel, built-in night sights, and was impossible to jam. It was also a folding stock, and a hell of a lot more compact. So, yeah... There actually were better weapons available, although I still prefer the human engineering on the M16 series.

The handwriting was on the wall as early as the Son Tay Raid--The issue M16 was too big, too bulky, and there were superior sights available. Even the Israelis and Finns were smart enough to put luminous night sights on their standard-issue weapon, something that apparently was a bridge too far for the A2 program.

The A2 looked really good to me, as a Sergeant helping run the company arms room. It was new, not worn out, and it sure seemed cool. When we got our first ones there around '88, it was the latest, greatest thing--But, looking back at it, from the vantage point of today, after spending 25 years on active duty? It was emphatically not what it should have been.

The major things wrong with the A2 design was that it failed to take into account a lot of the actual lessons of Vietnam, namely that even the M16A1 was too damn big, especially for what the cartridge offered. As well, there were a bunch of things that were added that were entirely useless, like that sight they took from the Colt LMG. The premise of that thing is flatly insane--Probably 90% of your shots in combat are taken at fleeting glimpses of the enemy at random ranges out to around 300-400m max, and they're giving us an insanely adjustable sight that's only really superior to the A1 sights past those ranges? Oh, and they didn't bother to give us any sort of night sight, when they had the opportunity? Don't even get me started on all the other things that a real "Product Improvement Program" should have meant, like better corrosion-proofing and coatings. Or, as another example that the Canadians were putting on their version of the M16, cold hammer-forged barrels with superior accuracy and life.

Let's face the facts of the matter: The A2 program was tasked with producing a better combat rifle. What it actually provided the troops was a superior range toy that didn't address many of the problems of the A1 at all effectively. And, when a better combat rifle came along, by accident, the A2 was dropped like a hot potato--That's how "right" the A2 program got it. The A2 actually had one of the shortest service lives as a front line combat weapon in American history, when you get down to it--It was finally fielded in mass numbers by the late '80s, and was undergoing mass replacement in the infantry formations with the M4 by about '95. That tell you anything?

The M4 itself is another travesty of poor program management; it was originally intended as a handier, more easily-carried weapon for self-defense by support troops. Because of that, they really never did thorough ballistic testing to see if it maintained lethality to the full range that the A2 did with the standard ammunition. Turns out, it did not--And, we didn't really discover that until the 2000s, when we finally did something about it. In the middle of a freakin' war. What year was Somalia, when that first appeared in combat situations, and what year did we get M855A1 into mass issue, again...?

There were apocryphal reports of lethality issues with the M4 and some of the similar weapons that the Rangers and Delta were using in Somalia. Nobody in the procurement system thought to do anything effective about it until reports started coming back in from Afghanistan, over ten years later, and the military started getting bad  press about it. Thus, the M855A1, which itself has some issues.

Then, there's the pathway by which the M4 became our standard individual weapon for front-line combat troops. If you recall, the thing was supposed to be for support troops like artillery and engineers, as well as drivers and such-like in infantry units. The original plan was, A2 for line infantry, M4 for support troops.

Only thing is, that's not how it worked out. Once the M4 started coming into the line units, and people got their hands on it, all of a sudden we're diverting them from the support bubbas over to the front-line combat troops.

Huh. Funny, that. Kinda makes you wonder about the whole "The A2 is the ultimate expression of the M16 as a combat weapon..." idea, doesn't it?

To me, looking back, it appears as though the A2 program was a rathole we never should have gone down--And, if you go back and look at the available information, that should have been clear. Just like the idea of an intermediate-caliber assault rifle should have been clear to the guys who adopted the M14...

There is copious literature available in DTIC from Army Research Laboratories, discussing the shortcomings of the M16A1 that were identified in Vietnam--With the recommendations that it be replaced with something shorter and handier.

For more handwriting on the wall, you can look where they tested and prototyped red-dot sights shortly after Vietnam. Colonel Bull Simon was the guy who put those on his men's carbines for the Son Tay Raid, where they proved themselves under fire. Post-Son Tay Raid reports recommended that such sights be investigated for general issue and use.

Took Big Army until the 2000s to pay attention, and realize the superiority of that sighting system over iron sights, especially under combat conditions where fussy little adjustable iron sights aren't really of use until you're in a situation where you really ought to be engaging with either your indirect fire, or your damn snipers in the first place.

No, to be honest, I'm going to stick to my position that the A2 and M4 should never have happened in the first place, and they should have paid attention to the actual lessons of Vietnam, developing something that would have looked a lot more like the M27 than anything else. Hell, Colt was even offering pistons back in the 1980s and 1990s, if we'd have wanted them...

TL;DR--The M16A2 was a mistake we shouldn't have made, and the M4 just compounded the error. Marines finally got the individual weapon right with the M27, in terms of size/barrel length. Piston, maybe not so much. Cost? Sure as hell not...

Quoted:
So readers have spent a lot f time expressing their opinions here, and that's a good thing.
But some need to go back and read the why and where for of the A2 changes, PARTICULARLY the ones I made to the trigger mechanism and butttstock.
I went out of my way, and in fact snookered some in the "system," by making these easily reversible at the battalion/2nd echelon level with parts that were readily available in the supply system.
So I ask you nay-sayers, how many commands were so unhappy with the stock length and 3RBC, that they replaced them with A1 buttstocks and standard M16A1 full auto trigger sets...?
Hello: "that reverse-ability was no accident."
Then go back to 1983 when the A2 was standardized, and count the decades it took for a 14.5" carbine to replace it...and when the Army did, it had the f'ing 3RBC...

And then there were these that Bean Counters would not roll with...https://www.AR15.Com/media/mediaFiles/19411/early_scope_concept-956230.jpg
https://www.AR15.Com/media/mediaFiles/19411/early_removable_handle-956231.jpg

Quoted:
So readers have spent a lot f time expressing their opinions here, and that's a good thing.
But some need to go back and read the why and where for of the A2 changes, PARTICULARLY the ones I made to the trigger mechanism and butttstock.
I went out of my way, and in fact snookered some in the "system," by making these easily reversible at the battalion/2nd echelon level with parts that were readily available in the supply system.
So I ask you nay-sayers, how many commands were so unhappy with the stock length and 3RBC, that they replaced them with A1 buttstocks and standard M16A1 full auto trigger sets...?
Hello: "that reverse-ability was no accident."
Then go back to 1983 when the A2 was standardized, and count the decades it took for a 14.5" carbine to replace it...and when the Army did, it had the f'ing 3RBC...

And then there were these that Bean Counters would not roll with...https://www.AR15.Com/media/mediaFiles/19411/early_scope_concept-956230.jpg
https://www.AR15.Com/media/mediaFiles/19411/early_removable_handle-956231.jpg