[foxyv]

The problem with this is how you identify the ammo used. If you print on the shell casing, it can be re-used after it is ejected from the rifle at the range leading to reasonable doubt about it's origin. There is also no way to tag the bullet itself. Tagging firearms and regulating them is much much easier. Can you imagine the police checking that each and every shell in a box of 300 is tagged?

With regards to the most recent shooter, as far as I can tell, their only parent was a grandparent who they shot and killed before attacking the school.