Why even have them in the first place? The self defence argument is thin compared to the facts around recent & historic shootings. Just on Christmas morning, some idiot father left a loaded hand gun on the kitchen table. His 2 yr old son grabbed the gun, pointed it at his own chest & pulled the trigger. BANG! One dead toddler. Who was this guy planning to shoot: Santa Claus? Did the Christmas pheasant make a break for the front door?
Some other idiot left his loaded gun in his back pocket & sat down in a movie theatre. Upon getting home, he realized he'd lost it BUT never filed a missing firearm report with the police. The same day, a school took a class of kids to see a movie & 2 eleven yr old boys found the gun. Fortunately, they didn't play with it or quietly smuggle it home but notified the teacher & the gun was spirited safely away. Another guy sat down with a loaded gun in his pocket in another movie theatre, the gun fired on its own & blew a hole in his @$$!!!
Too many guns are floating around out there accessible to unstable people. This Lanza woman was living in a town that had seen only 1 murder in the last decade. She had the rifle, 2 hand guns & 2 other guns. Who was she 'protecting' herself from: rogue Avon ladies? Her unstable son waited until she was sleeping, opened the basement 'gun safe' (what an oxymoron!) took her guns & murdered her in her sleep. This kid had no known history of violence & was no Arnold Schwarzenegger. So what if he liked a few violent video games: millions of people play them without magically morphing into maniacs.
Even the old tired 'then only criminals would have guns' argument is weak in countries like Canada & the US. The vast overwhelming majority of gun violence engaged in by criminals (gangsters, organized crime people etc.) is directed at other members & rival criminals. The odds of an ordinary person in America being shot by a Mafioso guy are next to nil. The odds of some gang banger crack-head in the ghetto taking the bus to your suburban neighbourhood to wreak havoc is also next to nil.
Plus, if your gun is un-loaded & locked in a safe somewhere & someone breaks into your home in the dead of night, what are you going to do: ask him to wait patiently so you can shake yourself awake, get the key to the safe, go open it, load & aim your weapon? Odds are that even if you irresponsibly & stupidly (like so many gun paranoids do) keep a loaded handgun in the night table drawer beside the bed, you'll wake up to find the bad guy pointing it straight at you. One can always cherry-pick & find the example of a home-owner who successfully defended himself using a fire-arm against an intruder but those are rare exceptional cases by far off-set by the amount who become enraged & shoot their wife, their kids, themselves or the kids find it, play 'bang-bang' & kill each other.
When will enough be enough?