I think it's what feels like (but statistically probably isn't, intellectually) an increasingly frequent string of unstable psychos slaughtering civilians that is making people gung ho towards gun bans, rather than clowns like the Oregon bunch (whose grand casualty total was one of their own who refused to be arrested alive).
My feelings have, and continue to be, that the right needs to be the ones to propose gun legislation. Something moderate to mild along the lines of bills that have been previously proposed and shot down, like the one cited in that CNN article above that put gun shows under the same background-check requirements as gun stores (which is just common sense, the gun show loophole is amazingly stupid) and prohibiting the mentally ill or people with connections to terrorism from buying guns (which is also a good-sounding idea, though admittedly harder to police and more open to potential abuse). This would give the GOP's moderate wing a massive amount of good-faith credit (we're compromising, look!) and give them a bedrock of principle to stand against anything more extreme (we'll go this far but no further on principle).
But right now the NRA has its hands around the throat of Congress and its head up the asses of the gun manufacturers, stifling any attempts at legislation. Meanwhile, every so often a deranged lunatic will shoot up a school or club or office building or something, and public outrage will continue to fester and grow at Congress's inability to 'do something', giving the far-left endless ammunition, pun intended and apologized for, to push their own harsher restrictions.