So I was trained using a full size M16A4, with the vest on it was pretty darn uncomfortable to shoot. But 95% of the people who rant and rave about the neccesity of having an m4 "clone" aren't wearing armour. The full size is really not that large, is cheaper, and easier (for at least me) to shoot. The weight is NOT that much different. The way I see it no matter what your carrying its going to be heavy after long enough. So why sacrifice accuracy for that cool looking tactical stock?