Many states don’t provide the federal gun-buyer background-check system with data about the mentally ill — and around 40 percent of gun sales take place without any background checks at all.
“We have a system that looks like Swiss cheese,” said John Feinblatt, a top adviser to Mayor Bloomberg who works on the issue for Mayors Against Illegal Guns.
President Obama has proposed closing gaps in the background-check system. Many of his ideas previously have been thwarted by NRA lobbying.
Surveys of gun owners show broad support for improving background checks, Feinblatt said. “The only place this is a controversy is Washington,” he said.