Health: was the gun bought in America? If not, why does being an American matter.
The problem with harsher punishments is that many of these criminals are the opposite of chachamim and don’t think beyond the next 30 seconds. And of course when it comes to terrorists and other mass shooters, dying in the process is part of their end-game.
However, gun-ownership by the right people can stop a terrorist in his tracks sooner rather than later. The problem is that we apparently can’t differentiate between friend and foe when issuing gun permits.