I think Todd's right. Too many mass shootings for the government to continue doing nothing. My assessment of the problem is that most of the proposed actions, short of a ban and seizure of all handguns and "scary black rifles", won't result in much of a decrease in firearm homicides in the U.S. Universal background checks for all firearm transactions were estimated a couple years ago when WA passed its BGC initiative were estimated to result in a decrease of between 1 and 2%. Of course any victim that might be in that 1 or 2% would appreciate the result, but on a national scale firearm deaths would continue mostly unabated.

Most of the mass shooters in the U.S. in the recent years did pass background checks, so expanding that ain't gonna' solve much. An assault weapons ban doesn't do much good either. We tried that a while back, and manufacturers simply build guns that fall just outside the definition of whatever's banned. If the gov't. bans "scary black rifles" the manufacturers will simply sell red and blue ones. Gov't. seizure of weapons just might provoke armed revolt, and I don't see that ever gaining much traction. I speculate that some kind of gun registration may be invoked, which will make many gun owners felons because they oppose registration. It might reduce firearm deaths in some measurable way, but probably not all that much.

I can't envision any legislation that allows lawful firearm ownership that also accurately predicts which lawful owners will subsequently become mentally disturbed and commit gun violence.