Thing is, Chicago has had a sky high crime and murder rate for a very long time, and went from no legal handgun ownership at all to it being allowed due to McDonald v. Chicago in 2010, took effect within a year or so, and now full and fairly administered shall issue in 2013.

Gun laws there are confounded by so many other factors in general crime and murder rates that I doubt much useful knowledge can be discerned until some number of years pass as the city returns to US norms of gun ownership and concealed carry.