People doing shooting - mass or whatever - rarely worry about anything but themselves and the voices in their heads.
It should be difficult to buy guns, but you are going to have to get mental health reporting through, and obamacare certainly is a big roadblock to that - and even has created a gap in mental health coverage.
I support tighter gun sales and ownership.
Too late for that, best we can hope for is to make it nigh to impossible for whackos to get them, although they still seem to get them - illegally.
As far as the stories go, they may well be true. I found links to a couple news stories, and if I was a gun shop owner, I wouldn't have sold a gun to the guys in both of the links. But of course, in order not to do that, I would have had to profile people and have listened to cries of discrimination.
Interesting facts from a LEO that I know:
Any person exhibiting any two of the three following traits or behaviours may result in gun (two of those three factors points to a possible future mass, serial, or spree killer) or other violence later in life. Although not entirely definitive, the traits point to patterns of abuse which may make the one abused more prone to violent behaviour.
Bed-wetting after the age of five.
Arson
Animal cruelty