Do not compare terrorist bombers to murders:
- 9/11. Boston, McVeigh and at least one convicted accomplice.
All of the situations listed involved at least two people or more. Unlikely to stop those. However, there have been over 100,000 murders in the USA since 9/11, most often done by single people, going it alone, and using a handgun.The amount of these can be greatly reduced by drying up the Black Market.
This can be done two ways:
Require that if you purchase a handgun, once a year, for five years, within a 3 month window, you go to a well protected drivethrough, put your guns in a sliding drawer, and have them compared to the information on file.
You will do this, because when you purchase a gun, you also have to purchase a bond, at a sliding scale price from 10 to 50 percent of the cost of the gun. If you don't show up, you forfeit that bond.
The reason for this is to reduce the number of gun flippers, who keep the Black Markets alive with cheap firepower. If you fail to do this, you will also be forbidden to buy additional guns for 5 years, and only one per year thereafter.
Way Number Two:
To purchase a new gun, you need three people to vouch for you, that you will not break any of the laws concerning guns. If they guess wrong, they lose one half of their next years tax refund. This may seem minor, but there is a second penalty: If they guess wrong they cannot recommend another person for 5 years.
This requirement will show at least a minor modicum of sociability. This avoid everybody going to shrinks, and provides at least a minor check on mental stability.
Notice that all this applies to guns new to you, and not the ones you've already got. You may be crazy as a bedbug, but you get to keep those.