The recent spate of killings gives a misleading impression. Since the peak years of the early 1990s, the number of murders in Chicago has fallen by more than half. In the first three months of this year, homicides were down by 1.1 percent. No one would describe the current murder rate as acceptable, but the city has made huge progress.

It has done so despite the alleged problem cited by Weis, which is the availability of guns, and particularly one type of gun. “There are just too many weapons here,” he declared at a Sunday news conference. “Why in the world do we allow citizens to own assault rifles?”

Actually, in Chicago “we” don’t allow citizens to own assault rifles. Elsewhere they are allowed for the same reason other firearms are permitted. The gun Weis villainized is a type of semiautomatic that has a fearsome military appearance but is functionally identical to many legal sporting arms.

And its bark is worse than its bite. As of March 31, there had been 87 homicides in the city. When I asked the Chicago Police Department how many of the murders are known to have involved assault rifles, the answer came back: one.