If you can find any good reference pictures, it would be nice if you'd post them. I have plenty myself, but not everyone is good. The M16 is probably one of the worlds best documented weapons, so I am not sure what you would want, but I attach a zip file that includes a pic showing a cut down labelled original M16 (trials) and two other pics showing the differences between the A1 and the A2 - I labelled the major cosmetic differences on one of those for ease of reference and left the other blank so you can see the detail. Hope it helps.