Editor, The Armory Life
Penetrating trauma, prevented...and that’s what'll most likely kill you on the spot. This is not inconsequential.
But if the back was deforming with a .22...odds are the 9’s or heavier calibers are going to do some serious blunt force trauma damage. Skull fractures, concussions, swelling of the brain...expect it. It will be roughly the equivalent of getting a solid hit in the forehead with the ball end of a ball-peen hammer.
It'll save your life, probably, but I doubt you'll still be in the fight afterwards.