The PATRIOT Act was passed because as a nation we were scared. Maybe we should all just take a few deep breaths and look at this as a complex problem that knee-jerk reactions won't fix.
There are definitely problems with gun accessibility for the suspected mentally ill in this country. Harris and Klebold had both been court-ordered into psychiatric care. Virginia Tech? Well, Cho was diagnosed with a severe anxiety disorder before the attack. Loughner was kicked out of college for being too crazy for people to feel comfortable around him, and campus police and the administration removed him until he had a psych exam (which his parents didn't bother with.) Holmes was referred to police for saying he was going to kill people. Adam Lanza it seems everyone but his mom realized was a bit off. It just goes on and on. There were red flags waving everywhere, but people just ignored them.
The Columbine kids found a straw purchaser. VT guy had no record because it's really tough to put one on someone who has never committed a crime, even if everyone around them things they're crazy. Loughner was a case of the college trying to wash its hands, just like Holmes. With Lanza the issues appear more complex, but he stole guns that his mom left accessible to him even though everyone around him knew something wasn't right with him. I'll even point out the Clackamas Town Center shootings were done by someone who stole a gun from a friend who most likely didn't secure it well. The Aurora shooter (Holmes) is the most pathetic case of the system failing, since his doctor alerted police, but apparently once he dropped out nobody cared to follow up.
So, maybe we should be looking at how we find a way to respond to tons of people seeing red flags but not reporting any of them rather than jump at a quick and easy solution that would be unlikely to actually prevent mentally ill people with severe anger issues from killing a lot of people.