I've had the misfortune of having six instances of bullet deflection over the years, all when having a seemingly clear line of sight through a scope. Two of those instances unfortunately resulted in a flesh wound of the deer, but extensive searches led me to believe that both deer survived. One instance resulted in the bullet hitting the deer in the neck just below the head, a full 18" from the point of aim. Another instance occurred on a 5x5 whitetail, one of my nicer bucks. Just a few minutes before the end of shooting time the buck came walking down the opposite side of a wooded draw I was watching. Resting against a tree I took the shot at 100 yards. The crosshairs were steady on the chest at the shot and the buck took off angling down the draw towards me. He stopped at about 30 yards, and subscribing to the theory of shooting until the animal is down, I shot him through the heart, dropping him on the spot. To my surprise there was only one bullet wound. The next morning I returned to the site of the shot and looked over to where the buck had been standing. I saw a spider web of small branches that were completely invisible to me the evening before in the low light.
