I think that the problem lies with Billy Bob, not the gun. It's not worth preventing the edge cases if that means reducing the average person's ability to defend themselves. Say that one person of the family had a pistol, and ran and got it while the Billy was busy shooting the others? The family member could then shoot Billy and possibly save a few family members. Guns are a means of personal power, and while loose gun laws mean that an unlawful person can get a gun, it also means that other people can defend themselves against said person, or other, non-gun-related crimes such as burglary.