The amount of elevation needed to hit a target at 1mile with a 5.56 caliber gun would be ridiculous, then you have to take into account windage; 5.56 is a very small bullet and would be effected by wind quite a lot as it slows down. even if by a miracle you did hit me, the bullet would have lost a lot of velocity and wouldn't be fatal anyway.
Anyway its all theoretical, I have never fired at someone a mile away with a 5.56 gun.