Like communism, it worked better in theory than in practice, and like communism, only the sad Old Guard wants it anymore. Bloomberg (h/t Instapundit):

Closing gaps in the background-check system would likely have only a modest effect on crime rates. But for gun control advocates struggling to stay relevant, the push for such changes represents a noteworthy shift—and a concession to reality. Having decisively lost the decades-old political and cultural argument over whether Americans should have the right to pack heat, they need to adapt to meet the demands of a public that wants to reduce the number of crimes—not the number of guns.

The guns were never the problem.