I am certain that any number of people who respond to this or have already responded will wax poetic on the need to eliminate what they think is the easy availability of guns. So, it might help to present a few facts on just what one must do to legally purchase a gun in Illinois.
Step 1 is to obtain a Firearm Owners ID card (FOID). This requires a background check by the Illinois State Police. It must be presented to purchase either a firearm or ammunition in this state.
Step 2 is to fill out Federal Form 4473. Presenting false information on this form is a federal crime.
Step 3 is to put down your money.
Step 4 is a 24-hour waiting period to take possession of a rifle or shotgun and 72 hours to take possession of a handgun.
Step 5 is to pass another background check in the form of a call by the dealer to the National Instant Check System.
Steps 2, 4 and 5 are not necessary for ammunition purchases. These apply to purchases from someone who holds a Federal Firearms License such as a dealer at a gun show.
For private sales, one must still present a valid FOID card. The seller must contact the Illinois State Police (this can be done online) and check the card's validity. A number will be obtained which the seller is required to keep for a period -- I'm not certain how long.
One other thing is worth mentioning. A convicted felon is prohibited from possession of either a firearm or ammunition. To do so constitutes a federal crime and can be prosecuted in federal court. Why this is not done more often is a topic for a different day.