Exit of the Bullet Against Pressure
If a bullet exits from the skin without any resistance other than the tissue resistance, an exit hold with subsidiary tears results. . . . If, however, the bullet exits from the skin against pressure from a firm or hard object in contact with the skin, the appearances of the exit wounds are different. . . . If the object in contact with the skin is hard and the bullet exits against considerable resistance from it, the exit wound may not only be round but it may show a rim of abrasion in its margins. Such exit wounds could easily be mistaken for entrance wounds. Exit wounds of this nature may be seen when the victim is lying on the ground or standing against a wall when shot and the exited bullet is stopped by the ground or the wall. They may also be caused when the exited bullet hits a belt, buckle, tough clothing or a similar object in tight contact with the skin.