Most of the threads I read where Kraigwy has posted, I usually keep my booger pickers off the keyboard, because he usually posts something very similar to what I would, except he's smarter and more experience than I. This time I feel like I need to add my little bit.
Definition of Ergonomics. Design factors, intended to maximize productivity by minimizing operator fatigue and discomfort.
On the M16, the saftey selector, mag release, and trigger are accessible by the right shooting hand. ( Sorry lefties, it's a right hand world...)
The bolt release is just behind the off hand, easily engaged without losing sight picture.
The only reason to break sight picture on the M16 is to pull the charging handle, and IMHO, that should be done before going into a hostile environment.
The only thing I personally dont like about the M16 is the forward assist. Should just have a bolt handle on the side, like every other battle rifle worth its salt.
Overall, the weapon is light weight, can be operated with a minimum of movement, is easily adjustable and mission adaptable. It is the essence of ergonomics in a weapons platform.