As for the 2nd Amendment, only the far lunatic fringe left actually want all or part of it abolished. It is the "well-regulated militia" part that is the hot topic of debate. Many "pro 2nd amendment" folks leave that part out entirely and go directly to the Right to Bear Arms.
If you want to keep rice from sticking to the bottom of the pan, coat the bottom very, very lightly with oil and place a banana tree leaf or two over the bottom of the pan. Then, put your rice in. Voila! Clean pan, no sticky rice.
Additionally, the prison system(and by extension, the entire criminal justice system) makes sure to keep crimes happening. Those with criminal and arrest records have high recidivism rates. Those with records have a much more difficult time gaining meaningful employment, obtaining an education(have little knowledge in securing educational loans), and getting the things necessary to succeed in life such as getting a place to live, bank account, and bills.
That is getting away from the topic as the shooter obviously does not fall into any of these categories(nor does the Va Tech shooters among many others). I'm not sure there is much we can do to prevent another instance of this happening as events like these are going to happen, like it or not. Hell, there is a much higher chance of dying in a vehicle crash.....so....life can be dangerous.....this isn't Star Trek, folks.
And yes...I've read the Superfreakonomics books as well as having a Bachelors in Criminal Justice and working as a Probation Officer...all gave me some insight into shit like this. I got tired of it...I paint and repair cars now, lol.