What year did the M16A1 with its various product improvements start to find its way into the hands of our fighting men?  

I think it was '64 or '65.  Im sure someone will be around shortly to fill in.

Nevermind.  

I got it.  According to the website I read the M16A1 was adopted on February 28, 1967.  

While early '67 may have been the date of adoption, I wonder how this translated to the M16A1 rifles actually arriving in quantity to our troops in Vietnam?

Enjoy...

The development was guided by the Army during the 1950s, which culminated in a field trial in Vietnam in the early 1960s. This led to its official adoption in 1964 by the USAF as the M16. Various modified versions of the M16 design were subsequently fielded under experimental designations, culminating in the M16A1.

The M16A1 was simply the M16 with a forward assist as requested by the Army. This weapon remained the primary infantry rifle of the United States military from 1967 until the 1980s, when it was supplemented by the M16A2. The M16A2, in turn, is currently being supplemented by the M16A4, which incorporates the modular flattop receiver unit developed for the M4 Carbine. Previous versions of the weapon are still in stock and used primarily by reserve and national guard units in the United States as well as by the U.S. Air Force. The M16A3 is a fully-automatic variant of the M16A2, issued primarily within the U.S. Navy.




~nb

Quoted: Enjoy... The development was guided by the Army during the 1950s, which culminated in a field trial in Vietnam in the early 1960s. This led to its official adoption in 1964 by the USAF as the M16. Various modified versions of the M16 design were subsequently fielded under experimental designations, culminating in the M16A1. The M16A1 was simply the M16 with a forward assist as requested by the Army. This weapon remained the primary infantry rifle of the United States military from 1967 until the 1980s, when it was supplemented by the M16A2. The M16A2, in turn, is currently being supplemented by the M16A4, which incorporates the modular flattop receiver unit developed for the M4 Carbine. Previous versions of the weapon are still in stock and used primarily by reserve and national guard units in the United States as well as by the U.S. Air Force. The M16A3 is a fully-automatic variant of the M16A2, issued primarily within the U.S. Navy. ~nb

The M16A1 was not derived from the M16.

The M16 and XM16E1 existed in 1964 through 1967.

The XM16E1 became the M16A1 in 1967 and existed along with the M16.

I don't know much about it but this is what I do know.

June '67 MCRD San Diego. We trained and qualified with the M14. Didn't see an M16 until later in (BITS) Basic Infantry Training School. November '67 I was issued an M16A1 at Khe Sanh CB RVN before moving up to hill 861.

BTW. December '67 we were issued new uppers that replaced the three prong flash suppressors with the bird cage type.

The M16A1 was simply a XM16E1 with a new name.  Colt refers to both as the Model 603.  Not sure when Colt started marking the 603 with the M16A1 roll mark, but it would have been after January 1967.

The improved rifle with the bird cage flash suppressor and chrome chamber began production in late 1967.  Was supposed to have been in August, but according to Congressional testimony it was delayed until October due to the UAW Strike at Colt's.  Replacement chrome chamber barrels entered production the month prior.

So about the earliest the improved M16A1 could have showed up in Vietnam would be November of 1967.  Here is an article dated 15 May 1968:

My unit [Co. C, 1/26 Inf, 1st Inf. Div.] was issued the M16A1 in late summer of 1968, don't remember the month.  The new rifles were brought to the our field location where everyone carrying the XM16E1, shotgun, or M14 had to exchange it for the new weapon.  There was a lot of discontent about losing the shotguns and M14s.