It's just common sense. If you buy a gun, Society has an interest in knowing that you own that gun and you should be required to carry liability insurance on any damage caused by that gun. If you walk into a gun store to buy ammunition, you should be required to show proof of ownership of a firearm that requires that ammunition and show proof of liability insurance for said firearm. There should also be a reasonable round-per-day limit on ammunition purchases. Any purchases of semi-automatic weapons or clips exceeding 10 rounds should be restricted to law enforcement or military personnel. Rather than making everyone's medical and mental health records available to law enforcement or gun dealers, everyone's gun and ammunition purchases should be available to medical professionals. If a possibly psychotic patient presents himself with a desire to do harm, the clinician should be able to query a federal database and see "this person doesn't seem to own any weaponry that presents a real and present danger to anyone", or "this person purchased 12 semi-automatic weapons and 5000 rounds of ammunition 6 months after filing for unemployment, 4 months after declaring bankruptcy and 2 months after his wife filed divorce papers in Lafayette County". A doctor should be able to file a "reasonable cause" block to further gun and ammo purchases and require that person's home to be searched and have any dangerous weapons legally removed and held in safe keeping until the individual is deemed responsible. This makes sense.