Well, handguns are for sure. And Rifles and Shotguns are legal but are "supposed" to be registered with the cops and said registration approval renewed annually (but nobody does that). And naturally those evil 'semi automatic assault rifles' are banned. Then again, if you live in Public Housing ALL firearms are banned..
Wait... you're right ALL guns are basically illegal in the Kingdom of Daley.
(Seriously, by Chicago's firearms laws Cap Pistols are supposed to be registered with the cops. That old Mattel Fanner 50 is a dangerous weapon don't ya know.)