when you can sit there prone and fire 5 rounds at a non moving target, there is good chance that 4 out of 5 will miss. Even accurate, scope rifles do the same thing so I'm not sure what magical aiming device you are using and how you are surviving 5 to 6 targets all firing at you with vintars and M4 from 100 yards away and living.
It doesn't matter how well aimed and timely my shots are, they will never go in the same place twice, often they won't even be close, and I only go for headshots.
I'm compensating for bullet drop, I'm aiming for the head, and I'm moving from cover to cover.