IMHO, any caliber works, but go for broke.
Jeff, I hope you have at least a 12g shotgun handy in your house. At some point, Deb Frisch is going to act on her impulses.
I want you anti's who read me to pay close attention to that posting. I will give you a little background. Deb Frisch is insane and an alcoholic to boot. She latched on to Jeff Goldstein's blog and threatened his son. Death threats, if I recall correctly. Jeff sought out legal action against her and got a permanent restraining order. Frisch has been arrested on various charges and yet still roams the streets. And now she's threatened Jeff's 70 year old mother.
Did I mention she's still walking around, free? The problem isn't guns, the problem is our judicial system that lets whack-jobs like Deb Frisch and criminals with rap sheets measured in banker's boxes walk free while our prisons are full of people who had an 11 round magazine in MA or got caught enjoying themselves too much with a banned plant.