Australiahad an official training manual (The Automatic Rifle-M16) published for general circulation in 1966 and would have been using them for a couple of years before that. M16
issue of M16's to NZ troops was mainly to officers, NCO's, and specialists who had other duties (radio operators, artillery observers, etc) while riflemen carried the SLR. As the war progressed the issue of M16's was more widespread, and from the end of the war until 1988 when the Steyr AUG's were introduced, it was the issue rifle for the Infantry, with SLR's being relegated to training and second echelon units. The official MG of NZ at the beginning of the Vietnam conflict was the L7 GPMG (FN MAG58), supplemented by L4 Brens and L2A1 heavy barrel SLR's, but for reasons of compatibility the M60 was issued, with the L4's and L2's being support weapons for Artillery, etc. After Vietnam the NZ M60's were placed in storage an sold off in 1988 (I had one in my collection for many years).