It was use of ball powder instead of cut tubular.Interesting clip, however there was no mention of what was allegedly a serious problem in Vietnam, namely the aggressive climate, ie high temperatures and humidity that speeded up corrosion lots and also corroded the brass cases leading to first rd jams.
While JHQ was open I read lots of books from their library, one was the story of the M16 and how not to introduce a rifle into military service. Can't remember who wrote it, but the corrosion was one problem mentioned along with the initial use of flake powder as opposed to ball, which supposed to be the norm along with chromed chambers and barrels. The final nail in the coffin was Colts claim that the rifle was self cleaning and therefore no kits were provided. Apparently soldiers were so desparate to clean the gun they use just about anything liquid, eg gasoline, engine oil and even water!
Next time I see him I must ask the clubs Vietnayam veyet what his memories are of the M16 back then. Always assuming that he is still breathing, he's older and more knackered than I am.