I've tried several times now when sniping that my shots don't register as a hit/kill. I've been very cautious about holding breath and not move when firing upon a target. So there are as few variables that can affect the shot. Today I did all of the above and I'm 100% sure that I was on target, but I did not get the hit/kill. After I fired the shot, the opponent when to a prone position and I could locate the impact of the bullet on the wall exactly behind the opponent.