Originally Posted by
scottryan
The M16A1 was not a replacement for the M16.
Both were concurrently serving rifles. Please do not keep perpetuating this myth.
Both the M16 (Colt 604) and Colt 603 (XM16E1) were adopted in 1964.
In 1967 the 603s name was changed to M16A1.
The M16 (604) did not go out of production in 1967 but stayed into produciton into the 1970s and had all the updates that later ARs had (fully chrome lined, modern bolt carrier group, modern buffer, etc).
The M16 was used by the Air Force and Navy.
The M16A1 was used by the Army, Marines, and Navy.
The only difference between these two rifles is the 604 does not have a forward assist and the 603 does.
I would also like to see you post this on here and on the retro forum on ar15.com so all of us can proof read it for technical errors.