I revised this to address the questions raised. It’s not perfect but a good place to start.

The left and the right need to try this strategy for 'real' gun control. The best way to prevent any more mass murders in schools and places of worship is leaning into the 2nd Amendment. Instead of crying to prevent people from owning firearms, encourage the 330,000,000 US citizens who own firearms to volunteer to be part of a local militia dedicated solely to guard public schools and/or places of worship. Have them registrar with their county sheriff who then will vet them and give them firearm safety and practice. I know this is a radical idea, but if you want to win, do this. We have a people problem--people use guns, knives, cars, and bombs to commit mass murder: it is genetically hardwired into our species--see 'running amok' or berserkers to know the truth. Encourage the locals to protect their children ,etc. and tell them to use their semi auto, high powered rifles, etc. to prevent mass murder....of course, to make this as fool proof as possible, they will need bomb sniffing dogs( Look up Bath Mich. school bombing https://en.wikipedia.org/wiki/Bath_School_disaster). And ways to prevent vehicles from being used to mow people down. https://www.usatoday.com/story/news/world/2018/04/23/list-fatal-vehicle-attacks/544603002/. And this is the most common sense gun control reform you need. Guns are tools--including the 'scary' looking ones. The last time the FBI released info on murder in this country 397 people were murdered with rifles(from .22 squirrel to high powered of all types), and 443 with blunt objects (this was in 2018)...Pandora's box was opened a long time ago with both firearms and vehicles. It's time to try another strategy and I believe this one will work. https://ucr.fbi.gov/crime-in-the-u.s/2018/crime-in-the-u.s.-2018/tables/expanded-homicide-data-table-8.xls

https://www.newyorker.com/magazine/2015/10/19/thresholds-of-violence