I'm new to this thread since as a Brit I thought I wouldn't have much to contribute. But would like to make a few comments.
I agree largely with ThisYouWillDo, taking a life can only be to defend yourself or thers when life is at risk. Not over a few bucks from the till or a TV set.
Of course taking away guns from law abiding citizens will not prevent crime by the baddies who carry guns. But it will prevent/reduce other gun casualties like domestic incidents and events like Virginia Tech. The interesting question would be how many honest citizens have actually saved themselves because they had a gun. I don't know, but imagine proportionally few.
The fact that UK has strict gun controls yet gun crime is increasing is misleading. Perhaps it would be even higher without controls. What sort of crime, lets see the breakdown. My guess is its gang related not really burglary and shooting the home owners.
Personally I cannot see any long term solution coming from everybody having or carrying a gun. True perhaps if honest citizens are unarmed and only criminals haev guns it may ger worse before it gets better. But what's the alternative long term.
Lastly, that americans look to the constitution as justification I find strange. America today is not quite the same. No maruauding Indians (you killed them all) or other risks that the right was intended to protect citizens against. So whatever the case for or against, the consitution certainly needs updating.
Just my two cents worth.