Like alot of people, I prefer the A1 length buttstocks. I'm curious as to why the military changed from A1 length to the longer A2 length buttstocks?

It was the Marines who demanded it - particularly their Marksmanship Unit.  The longer stock is better for National Match type shooter - but worse for 'combat' applications.  Same deal with the sights from the earlier rifles to the A2.

The USMC just wanted a better 'match' rifle.

Thanks for the reply Forest. But why did the USMC want a better "match" rifle? Did the USMC Marksmanship Unit's request basically dictate what all services received because no one really was bothered by the change at the time? Or did they want the change just for shooting in matches/non-combat type situations, which I would find hard to believe?
I'm not doubting you, I'm just trying to get a little more info on this.  

M16A2 - designed by and for range wienies.

Speaking specifically about the fully adjustable sights and the overly long buttstock.

G-Code,
The USMC Marksmenship guys have ALOT of input into the rifles the Marines adopt (witness their recent choice of the M16A4 over the M4).  The USMC adopted the M16A2 first IIRC, for some reason the US Army just 'went along' 2 years later.

I'm sure Coldblue could answer this.  You might want to ask him in the Rifles/Uppers section.

Can anyone tell me what the length differences are there between the two?

I'm in the middle of a sneezing spell and I have three daughters.....so I am easily confused.

5/8" I believe.

Dave S

For those who care, I emailed Dave Lutz (Coldblue) his IM box was full, in hopes that he would respond to this thread. I hope he does so that we all can learn what the real story behind this change was.

Gee, I think that the A2 buttstock is too short.

Firstly and most importantly, the Marksmanship Unit at Quantico had little to nothing to do with the development or final design features of the M16A2.  Contrary to what appears in some modern Marine Corps History Books, we infantry offices that ran the program knew enough about range and re-qual shooting to consider this in considering changes; while maintaining a "feature balance" and not screwing up a great assalt rifle. (Note: one of these officers (Majors) was/is now BGEN John Sattler, Commanding General 2nd Marine Division--just in case someone wants to confirm any of this) In fact, the only issue they (the bely shooters) had (and lost) was making the barrel heavy throughout.  But this was really just one guy (Major Bruce "old dad" Winchensen) who actually worked for the same LtCol Dick Moresco at the Firepower Division of Quantico's Development Center (these days called PM Ground Weapons, MarCorSysCom).
Bruce was assigned to run the Operational Testing, some of which was hosted by the Marksmanship Unit, but the troops were grunts from 2ndDiv and a Squad from Ft. Benning.
Bottom line is that the "changes" came from my side of the equation as I dug most of these out of the woodwork at Picatinny Arsenal and Colt in Hartford.  For example, the basis for the A2 rear sight was from a relic LMG Colt had forgotten about from the 70's that I found in their gun room, and one of their guys (Rob Roy) carried it (upper receiver) through Colt's Security under a coat one afternoon so I could take it back to Picatinny for evaluation and modification.
Part of my job was not just coming up with the changes needed, but ensuring we were not making mistakes.  So I was touching base with all concerned, including the Army's Human Engineering Lab at Aberdeen Maryland.  There was a fellow there (Paul Ellis) who had a book of human (95% centile) human size parameters.  I remember one illustraion of how far/close the shooter's eye needed to be from the rear sight, ideal length of pull etc.
Well the "ideal for the 95% Soldier stock length using a rear mounted peep sight was a full one-inch longer than an M16A1.  So making the stock better fit American size humans was put on the list.  However, it ended up being limited to 5/8" because that allowed the A2 to fit in the many thousands of standard armory M12 Rifle Racks, and not adversely increasing life cycle cost was one of many overiding factors meant to control my enthusiam for change that had been imposed on me by my boss, LtCol Moresco.
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Thanks for respondng Coldblue, this kind of info is just what I was looking for.

Cold blue-

Excellent response! There are so many story about "why" and no one really knows the truth.

The best way to get the true story is straight from the horses mouth. Thanks for being part of the forum. [:)]

ls

ColdBlue interesting on your use of the Aberdeen human engineering figures.

I've recently used the ones NASA has on a personal project.  When I was reading the specs I came to realize that if you use the 95% person data you make your design usable by 95% of the population (meaning the bigger guys can fit in it).  However, it means for the average (50%) guys it [i]will[/i] be on the big side.

So by building a stock to the 95th percentile it automatically was too long for most of the rest of us.

I was never much good at "statistical math", but I've always thought of 95 centile Soldier as appling to the physcial demensions of men (at least way back then) that were in the military, not the human population at large.  So I've always assumed that encompassing 95% was like streching the "bell curve" to cover most of us.
Of course we realized that some smaller statue users would find the A2 stock too long.  So the change came in the replaceable stock, not the receiver.  That is where the Spacer came in, as this idea did not require the buffer tube to be extended, and also allowed the Spacer to be removed if desired, and the original A1 length stock installed. That is if you also had the original shorter-length Upper Buttstock Screw, and the also shorter Lower Sling Swivel Screw.  By the way, the Lower Sling Swivel Screw had to be changed because the new material used in the A2 Butstock would not "flow" properly if the slot for the swivel was left where it was in the A1 stock.  
This is another good example of "no free lunch" in firearms design, I mean we come up with this great new stronger, beter, etc. material for the stock; mold it in such a way that there is an internal rib running the length of the stock (i.e., the A1 stock was actually just a hollow/foam-filled shell), and we got to design a new Lower Sling Swivel Screw because of "flow" or lack there of.
ColdBlue sends...