Why would you think that? That a psychopath who often spends weeks or months planning to kill people is going to be dissuaded by that, when there are black market ways to purchase or construct a firearm of their own?
Evil men will always find the tools they need to dispense their evil.
Actually school shootings is a good reason for more guns not less. There have been a number of would-be mass shootings that have been stopped by armed Good Samaritans, either off duty police or civilians with carry permits. Much like overall crime, this is a distributed problem and you don’t usually fix distributed problems with centralized solutions.
Yeah but think that through. If you want to get rid of Dad’s gun, you have to get rid of pretty much every Dad’s gun. And that has significant effects beyond just school shootings. It means every parent who used a gun to defend their family from harm now is defenseless.
Every year there are about 10,000 to 15,000 firearm homicides. 100 or less are due to terrorism or spree shooting. In contrast, per Wikipedia, there are somewhere between 67,000 and a few million defensive gun uses each year. Most are where a criminal sees a gun and runs away. Take away Dad’s gun and you get rid of almost all those defensive uses. And maybe you stop some or most of the 100 spree shooting deaths. Seems to me like doing more harm than good.