Hi Guys
The british Army purchased 10,000 Ar15s before the US army even adopted the rifle.
The Ar15 and early M16 does not have the forward assist. All photos in the 70's and early 80's are the Ar15's or early M16's.
SAS/SBS units may have used the M16A1 in the Falklands but not the Marines who would have used the Ar15/M16. There are defently pictures of special forces with the M4 Carbine.
After the Vietnam war where about 100,000 rifles were tested the M16 was modified to have the forward assit plungeralong with other small modifications and was adopted by the American Army became the M16A1 General Service rifle.
It was proberly the late 1980's early 1990's when the later M16A1 came in to service as stocks of the older Ar15/M16 where exhausted through wear and tear.
I have that picture of the guy in Ulster as well and I have seen the same guy in another photo either earlier or later in the photo sequence which shows the Right hand side of the rifle and it shows it as a Ar15/M16 not the M16A1.
The Ar15/M16 was issued in NI to provide the troops on patrol with a weapon that had a fully auto capability along with on occasions the G3 (with shortened barrel) made by Enfield.
The M16A2 was a Infantry sugested modified rifle which seems to have been issued first to the US Marines in 1982 and the late 1980's to the US Army. The M16A4 was a fully auto variant and was issued aparently to some US units at the same time as the introduction of the M16A2. The A2 other than looking like the M16A1 it was a complete new rifle (Example FAL and SLR one of the same but different rifles) Heavier barrel, 3 round burst mechanism, new cone flash hider which supposedly stopped mud getting in the barrel when the barrel was rested on the ground etc etc.
I have pictures of a Para Pathfinder platoon of 5 Airborne brigade taking part in an excercise "Winged Crusader" 1993 equiped with M16A2's.
Other than Specialized units it is not common to see normal units using the Ar15/M16 outside certain theaters' Belize, NI and and the Marines in the Falklands war but again the latter it was not a common sight.
If you are thinking of getting a M16 for the 1970/80's get the vietnam version with the cone shaped flash eliminator and not the ones with the round flash eliminators as you will be at least 50% more correct than if you used the later A1 specs.
ta
Jon