So Jimdandy you support universal background checks? It seems like that from your answers. None of these laws work without them, the person just buys from a non documenting source and all the effort is wasted.
Even with that as a given you just break it up into two crimes, one to steal/illegally buy the guns, one to commit the violence.
The reason I used the example's (French resistance, Warsaw Ghetto) I did was to show that determined people will get the weapons some other way.
With a little creativity 8 or 10 gas cans, gasoline, and chains for a buildings doors I could out do any of these guys in death toll.
We're going to have to treat the person or stop/kill the person. Trying to remove complete access to deadly weapons just isn't practical.
Gaily bedight, A gallant knight In sunshine and in shadow, Had journeyed long, Singing a song, In search of El Dorado