Aside from the current debate, I can't understand how Americans don't want to do anything about this issue. A guy on a no fly list can still legally buy a gun in this country. Why do we accept this as the norm? If we aren't willing to try anything to stop American citizens from killing each other, why care if terrorists come here to do it?
America is gradually and far too slowly becoming more progressive. As newer generations become more educated (which correlates with being progressive), the far right is getting more desperate in motivating its voter base. At this point, all it can do with that is basically create a fear-based hot button issue rotation that concentrates on those voters -actually- being the ones persecuted or in danger. Therefore:
Regulating guns = taking your guns for you
Being more tolerant of other people = taking away your free speech
Making sure religion is removed from the government = banning Christianity
Allowing equal rights for homosexuals = taking away our way of life
etc.
It's not as bad as it seems, really. The issue is that what is dying screams the loudest, so you're basically hearing the last and loudest flailing of a dying breed as they try their best to hold on to things, and a machine caters to them. But due to how things are framed, and now that the political system is basically soundbyte based, there is just enough of this left to effectively block real movement on many issues.