You have to remember that NATO type rounds do not expand like a hunting type bullet does. It is possible for a bullet of that type to pass through soft tissue like a brain without doing much damage at all. His skull probably took much of the shock out of the bullet, and slowed it down significantly.
Understood. I have a ballistics chart on a side door of the CT suite I work in. With tangential reconstructions of the accumulated data one can correlate the actual path and figure in to the equation the shock effect to the surrounding tissue of the projectile. You then toss the data into a 3D generator so the neurosurgeons can see before they chop. Knowing what I do, semi-jacketed Federal Hydra-Shok magnum loads is what I would recommend for household uninvited critters. It helps to work midnites in a Level One Trauma Center in Detroit to glean info.