like everything started with a picture, and unlike the saying picture paints a thousand words, this particular picture isn't representative of the real situation. try the video link and you'd at least understand the purpose of the fire. it is not like a spray-and-pray thing, however, in this particular situation, it was like used as cover fire. likewise, given the situation, you wouldn't expect the soldiers using m16, with their inherent effective range, to actually be using their sights and painstakingly getting a clear target before squeezing the trigger.