Although I agree strongly with federal Judge Larry Alan Burns and many others about banning the possession of assault weapons, those weapons are not our main problem. By far most killing is done with handguns.
Killings by means of assault weapons are comparatively rare, but they draw the most attention because they are very dramatic and receive much national media coverage. Twenty-seven murders in Connecticut is terrible, but about 10,000 in the U.S. in one year is much worse and doesn't get the publicity; it's just killing as usual, the American norm.
Of course, it's easier to ban assault weapons, which relatively few own — and with our current politics, the easier path might be the only one possible.