Faced with rising crime, the only "solution" available to Daley is more gun control. He has to do something. It's not necessary that it works. A city-wide ban on handguns obviously won't do anything to diminish gun crime, so the next step is a statewide ban. When that doesn't work, he'll lobby for a nationwide ban.
There are two facts of prominence in this story: First, that the guns most associated with the public image of gang violence -- the assault rifle -- is the least to blame. Second is that gun control is completely ineffective at stopping gun crime. It only disarms citizens and makes them dependent on police and politicians for their safety. Hence, the renewed cries for more gun control.