Another reason nothing will or should happen, mass murderers are not easily dissuaded. Someone doesn't just decide that they want to kill a dozen people, find out that getting a gun is a little more difficult, and then call it off. They will make all the applications, jump through any hoop, or steal one as a felon.
The only way to really make a dent in this sort of thing is a full handgun ban, possibly coupled with a full shotgun and long gun ban. Thats it, full ban of everything that shoots, no guns, only cops and some provision for people who need a gun for a competition. I know people like to talk about how stabbings are high in the UK and how thugs over there moved on to carry knives, but a full gun ban does have an impact, and its a lot more difficult to mass kill with a knife.
We'll never do that (nor should we). Guns are deeply ingrained in our culture, always will be, and ownership enjoys the protection of our strongest law. We recognized a long time ago that gun ownership has a price that must occasionally be paid in blood. We're willing to pay that price, and other countries are not.
If you aren't willing to ban guns, then gun control is a useless response to mass murder. A gun ban might be the goal for some of the Brady people and the motivation might be to slowly get us there, but those who say "oh I don't want to ban guns, we just need more gun control to cut down on these tragic events" are spouting a bunch of feel-good nonsense.
how many emo kids does it take to change a lightbulb?
none they just sit in the dark and cry