Over the years, I have consulted with many people who were disqualified from possessing a gun due to a criminal conviction, a protective order, etc. Some of those people have told me that they knew themselves to be prohibited, but tried to buy a gun anyway to see what would happen. Doing so is a very bad idea.
Federal law prohibits those convicted of felonies and certain other offenses from possessing a firearm or body armor. That law is codified in 18 U.S.C. § 931, which provides as follows:
In Illinois, 720 ILCS 5/24-1.1 makes it a crime for a person who has been convicted of a felony in Illinois or another state to possess a firearm or ammunition:
Iowa law prohibits people who have been convicted of a felony, misdemeanor of domestic violence, who are subject to a protective order, or have a juvenile adjudication that would have been a conviction if they had been an adult from possessing firearms or ammunition, under Iowa Code section 724.26.