Ref Columbine: In addition to the shootings, the complex and highly planned attack involved a fire bomb to divert firefighters, propane tanks converted to bombs placed in the cafeteria, 99 explosive devices, and car bombs. https://en.wikipedia.org/wiki/Columbine_High_School_massacre#Gun_control
To refresh our memories about Columbine....
During the Columbine massacre, in which 15 people were murdered and 21 injured, a total of four firearms were involved. The murderers also employed four knives and 99 explosive devices.
Of the firearms, only one qualified under the 1984 federal law as a banned “assault rifle”. One firearm was a doubled barreled shotgun with a shortened barrel. It has long been a federal felony to saw down the barrel of a shotgun and it was also a felony to possess such an altered weapon.
Every single explosive device was a federal and state felony to assemble, possess and use, and to use in the commission of a crime.
If the memory of Columbine is ever brought up today, the failure of the law to stop the use of explosives in a school massacre is never mentioned. It is never mentioned because that gets in the way of a Gollum-like fixation on the ugly and scary guns.