Besides that you can build a single shot shotgun for about $20, with stuff from your local hardware store.
And that, I think, is kind of the general idea. Make sure that only desperate goofballs have guns, and that those guns are single-shot home brew specials that are singularly ineffective for mass killing.
You could sit in the dark with your home-built single-shot (or hey, go nuts and make a double barrel), Walter Mittying to your heart's content as you eyed the security cams and waited for the Anti-Christ.
You paint an appealing scenario, and a much safer one.