Bullets and Car Metal

Below is an example of the effects of bullet construction materials and powder loads upon the damage to an automobile fender.  The plain lead bullets will deform (flatten) when they meet the same resistance as jacketed (metal wrapped) bullets that tend to keep their shape.

 As the plain lead (or hollow point bullet) deforms, it increases in diameter and transfers energy to the metal causing it to dent “inward” resulting in a crater.  That crater is highlighted by the paint broken free from its bond to the underlying metal.  The measured diameter of the resulting bullet hole will be greater than the nominal caliber (diameter) of the bullet.