There is no way to know if increased regulation would have stopped this from happening.
This guy decided to kill a bunch of people including his mother, I suspect if guns were not easy for him to get at, he might have worn explosives, who knows.
Yeah because explosives are even easier to get...
Bottom line is no matter how hard it is to prevent, the responsibility is to do everything you can withing reason. And better regulation, not necessarily even an increase, just more than slips of paper entered into a goddamn spreadsheet about ownership transactions. This isn't animal skins at the trading post, these are deadly weapons.
You can say this was the inevitable result of American decline, guns and mentally ill people, etc. But you don't have to accept it.
People will complain the government is monitoring everything they do and even then you are going to flood a small agency with an abundance of information they have no clue what to do with rendering it ineffective. I think stronger enforcements on earning a license, ban on using certain firearms that are not used for hunting except in permitted areas and mandatory psych tests should be required.
they could do it in a year or less. If they were resolute and not bound by external politics, they could do it in a few months. Have requirements, and documents set, ready and available, and required. Anyone who wanted a legal sale would have to download or request the fax. They could revamp the databases to hold useful user information, and expand it to support the new responsible and fit owner's evaluation check. The
hardest part would be deciding how deep a level of psychological evaluation is needed. Do they really need a medical eval, or just an administered test, like the one you take at the NRA, 40 minutes of questions and re-questions asked from different angles about ethics and violence and gun responsibility, etc. Maybe have a psychologist review and redmark them, etc. People can complain all they want, but this doesn't even have to be a federal thing. They license with the state already, the state could run the database. (And no, don't leave it up to the states to design it, they'll shit it up and use it as an excuse to spend more money.)