Nope, blame a system which allows someone who is under treatment for
depression yet can walk up to the counter in a gunshop, slap down a
credit card and walk out with a pistol and ammunition...no check, no
wait...

Doesn't work that way. People under treatment for severe psychiactric
treatment are not allowed to purchase firearms. Handguns have a
mandatory waiting list and non-residents can't buy them anyways. And
everyone is suppossed to get checked.