I saw it yesterday. I had no idea the Australians had so many M16s!!
I think the director couldn't find enough SLRs.
Generally there were 3 per Section, sect commander, first and second scout
Interesting. What was the rationale behind this?
Section Commander has may things to do and many things to carry. The M16 is lighter than the SLR so it suits the Section Commander role.
The section scouts didn't all have M16s at the time of Long Tan due to issues of supply. Some did, some still had F1 submachineguns firing a 9x19mm (9mm NATO / Luger) cartridge. The M16 did replace the F1 quickly as the F1 and cartridge were fairly useless.
The unnecessary dramatisation spoiled the movie. As an example, in the movie Pte. Large attacked his Company Commander during the battle. This did not happen in real life, and would not have happened. Similarly the NZ FOO was far more competent than the contempt than he was treated with by the CO. In the end, his calls that afternoon prevented the destruction of the company, then a follow-on attack of the Task Force base at Nui Dat which would have been bad for the ATF.
