M16a1,2,3,4

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Charleo0192

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I've noticed several guns ending with A1, A2, A3, etc (like in M16A2). I was told years ago what that meant (The stock of the gun). I'm no longer sold that A1, A2, etc is the stock. I've looked a little around the internet but come to no definitive answer.

Is it indeed the stock? Or is it the updated version of the previous? Is it different for different guns?


So please will you help me by clearing this up for me? I'd really appreciate it.
 
It simply designates different variations of the M16 family, which were used by the different branches of the armed forces. As for the stock, the M16 and M16A1 used the same shorter fixed stock, whereas the M16A2 - A4 us the longer stock.

The M16 and M16A1 were very similar. Both were 1 x 12 (for the most part, IIRC), 20" lightweight barrels, fixed carry handle, and semi auto and full auto select fire. The M16 lacked the A1's forward assist. Other than that they were identical, but I could be mistaken. The M16 was used by the USAF. The Army used the M16A1. I don't recall which model the Navy and Marines used.

The M16A2 - A4s all had heavy government profile barrels. They also featured a barrel with a twist rate of 1x7. The A2 (which was used predominantly by the USMC) had a fixed carry handle, whereas the A3 and A4 had a flat top upper receiver. The A2 had a 3 round burst feature in place of full auto. The A4 did as well I believe, but I think the A3 was fully automatic. Again, I'm a little fuzzy on that detail.
 
Definitely not just the different stocks. For example, the M16A2 has a different rear sight, and a longer stock, and a different fire control mechanism. (three round burst rather than Full-auto.) The A3 has the same modifications, but retains automatic capability. The A4 features a detachable carry handle rear sight.


Edit: JAD0110 beat me to it. Much more descriptive, too.
 
From what I remember of our A3s, they were either semi- or full-auto (no burst), and did not have a detachable carry handle. I don't remember the twist rate, but we shot both M193 and M855, so it must have been at least 1:9. Wiki says 1:7.

Wikipedia has a pretty good article on the M16.

http://en.wikipedia.org/wiki/M16_rifle

ETA: I was in the Navy from '01-'08, and not in an arms-related job. We got issued A3s as guard weapons or for repelling boarders. I carried a Mossberg 500 or a Beretta M9 a lot more often than an M16!
 
Last edited:
willypete said:
From what I remember of our A3s, they were either semi- or full-auto (no burst), and did not have a detachable carry handle. I don't remember the twist rate, but we shot both M193 and M855, so it must have been at least 1:9. Wiki says 1:7.

Wikipedia has a pretty good article on the M16.

http://en.wikipedia.org/wiki/M16_rifle

ETA: I was in the Navy from '01-'08, and not in an arms-related job. We got issued A3s as guard weapons or for repelling boarders. I carried a Mossberg 500 or a Beretta M9 a lot more often than an M16!
Click to expand...
Me too! I was in the navy from '00-'06 and carried the M16A3 maybe 4 times outside of training. All the rest of my watches were with the good old Mossberg 500. I don't have any combat time or anything.

The A3 we had was full auto or semi with a non-detachable carry handle.
 
A3 same as A2 but with full auto only setting, no burst fire.
As far as I know, FN still produces them in limited numbers for the Navy.
A4 is flat top, most are burst fire but these have also been built by FN as full auto selective fire weapons in limited numbers. All these rifles use a 1-7" twist, no A2 or later rifles were ever made for military with anything but 1-7" with the exception of a very few special operation rifles that used 1-8" commercial production barrels.

A1 is improved version of M16, better furniture, trapdoor stock, teardrop forward assist, (which M16 did not have), closed slot birdcage flash suppressor, (M16 used a truncated open slot flash suppressor), and reinforcement fences around rear of receiver to takedown hole, at front pivot hole, and around magazine release.
Early M16 rifles had non chrome lined bores and 1-14" twist, mid production M16A1 had chrome lined bore and 1-12" and late M16A1 had chrome lined bore and chamber and 1-12" twist.HTH
 
And the M-16 and M16-A1 did not have the brass deflector bump just behind the ejection port.

It may be because I trained on it and carried it, but I much prefer the A1.
 
I went through the repair certification course on the M16A2 and they were just starting to really issue them when I ETSed in '86.
82nd Airborne had them in limited issue as early as 1984.
 
IIRC:
M16: Triangular handguards, 3 prong flash hider, full auto (no forward assist)
M16A1: Triangular handguards, 3 prong flash hider, full auto, chrome lined barrel/bolt, forward assist
M16A2: Round handguards, A2 (birdcage) flash hider, 3rd burst
M16A3: Round handguards, A2 flash hider, full auto, flattop (detachable carry handle)
M16A4: Round Handguards, A2 flash hider, 3rd burst, flattop (detachable carry handle)

M4: 14.5" Barrel, 3rd burst
M4A1: 14.5" Barrel, full auto
 
Is there an A5? That would be rail system, full auto instead of burst? I thought there was an analogue to the A3 also, but I would be surprised if it were anything but extremely uncommon.
 
DoubleTapDrew said:
IIRC:
M16: Triangular handguards, 3 prong flash hider, full auto (no forward assist)
M16A1: Triangular handguards, 3 prong flash hider, full auto, chrome lined barrel/bolt, forward assist
M16A2: Round handguards, A2 (birdcage) flash hider, 3rd burst
M16A3: Round handguards, A2 flash hider, full auto, flattop (detachable carry handle)
M16A4: Round Handguards, A2 flash hider, 3rd burst, flattop (detachable carry handle)

M4: 14.5" Barrel, 3rd burst
M4A1: 14.5" Barrel, full auto
Click to expand...
The A1 did not have the 3 prong flash hider, in the late 70's at least, and instead had a full birdcage type flash hider, A2 on it is solid over the bottom half. Presumably to reduce stirring up crap when prone and/or to act as a muzzle break.
Again, also from A2 on the built on brass deflector.
 
We had clip on brass deflectors for left hand shooters of the M16A1 while I was in service but nobody ever seemed to ask for or use them.
I can't ever remember issuing one from the arms room.
 
If I recall correctly, another difference between the A1 and A2 was they added an elevation knob to the rear sight, and the buttplate wasn't rounded on the edges. I do recall the change being more welcome in my unit than the reception the M9's got when they showed up to replace the 1911's. Funny thing was- I don't think anybody in the group of guys I hung out with could really articulate why. Lord knows more than a few of our .45's were well ready for retirement.
 
During 1967, in Vietnam (and out of country for the Special Landing Force (SLF)), the 3rd Marine Division was issued XM16E1 models of the M16. I was attached to 3rd Marines out of Khe Sanh at the time. Some folks talked about this period in the book, "The Hill Fights, The First battle of Khe Sanh" by Edward Murphy. Murphy has an extensive appendix entry on the problems of the M16 during this period.

Because I was attached I managed to hang on to my M14 into my second tour in 1967, then I was "forced" to turn it in for a "Matty Mattel". I turned the issue rifle back in immediately and went over to the local aid station and rummaged through the "KIA barrels" to piece my rifle together. The "KIA" barrels are where KIA equipment was dumped including rifles, handguns, machine guns and M79's too. We used to pick through them when in the rear to get new or better or more magazines and other equipment too.

IIRC I used a E1 upper and lower, with a A1 buffer and recoil spring. E1 carrier with a A1 bolt. In those days I knew which manufacturer was not screwing up the chamber specs, and had generally more reliable equipment. My "Franken Rifle" was more reliable than most, but then the worst problem remained the terrible 20 round magazines. I carried only 16 rounds in my mags, and a pair of slip joint pliers to bend them square again. The distortion of the magazine bodies were a VERY common occurrence.

If you really want to know what the XM16E1 in Vietnam was about I Also recommend Jouster dot Com look under Sea Story's, where LtCol Culver tells the best rendition of what we went through with that POS in Vietnam. He was with 3rd Marines when I was there, but I did not know him when he was a Lt, personally. I was a Corporal during that period.

Good luck.

Fred
 
Yeah, as I recall in the mid-1970's RA, we had Mattel rifles with birdcage flash hiders closed on the bottom, triangular hand guards, fixed carry handles and forward assist. Don't know what that would make it? But, we carried a fair bit and I seem to recall the pieces pretty well. Mine was from Hydra-Matic Div of GM :)
 
Yeah there is an A5... the Marines are adopting it. It is a flat top with a full auto trigger group and a 7-position Vltor stock. They adopted it because the Marines like the longer 20" barrel, but like the collapsible carbine stock better for use with armor and with the currently taught close quarters shooting positions.
 
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