It is unrealistic to expect drastic and immediate changes to the law which governs the purchase of a firearm in this country.
The issue does not need infringe on our Constitutional Second Amendment rights; those requiring self defense in the comission of a crime should be allowed to use deadly force if necessary. Stricter legislation regarding purchasing guns may help hedge the number of persons with mental illness or violent histories from purchasing weapons.
Clean criminal background checks should be required to purchase firearms, and evidence that no mental illness exists. The federal govt. should enact a body designated to police this issue & create law, not each state. In regards to crime, persons who allow their firearms to be used by unauthorized parties should be prosecuted.