I was going to point that out as well, however the AR-15 came out in the late 50's based on the AR-10 prototype. The M-16 is the military designation of the original AR-15 prototype introduced to the armed services rifle trials and lost our to the M1A1 in 1962 only to be adopted in the late 60's (I want to say '66, but can't remember the year) when the M1A1 was routinely outgunned by the AK-47 armed NVA.
M1A was adopted in 1959. The M-16 in 1964.
Where did you come up with that retarded remark?
The M1A1 was the folding stock paratrooper version of the M1 carbine. I’m sure some were given to ARVN forces, but they weren’t generally issued to US troops in VN. Maybe you were thinking of the M14?