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.
The reason why it is so unwise to try and purchase a firearm if you are disqualified is that doing so is a crime at both the state and federal levels. Every state, including Illinois and Iowa, make it a crime for a person who is not lawfully able to obtain a gun to attempt to do so. The Federal government has a similar law. Thus, a person who is disqualified from gun ownership who tries to buy a gun will be committing a serious crime in that attempt.
I have represented clients in Iowa and Illinois, in both state and federal court, on gun-related charges. Even in cases where a favorable outcome is attained in court, the process of being charged, facing an arrest, and dealing with a case that could result in a lengthy prison term is never pleasant. I know that every client of mine who had such a firearms charge would have gone back in time and not obtained or attempted to obtain the gun if they could have done so to make the case go away. Since there are no time machines, clients cannot do so once charged. But, those who are disqualified from possessing a gun can and should refrain from trying to obtain a gun, as even attempting to do so is a crime for which they may face prosecution.
For those who have been banned from gun ownership due to a criminal conviction or other disqualifying event in Illinois or Iowa can seek a restoration of their gun rights. This is a somewhat involved process that must be handled properly in order to have the best chance of succeeding. My firm has represented many clients in Iowa and Illinois to seek such a restoration of their gun rights. More information can be seen in our gun rights restoration for Iowa and Illinois residents article. Properly seeking a restoration of gun rights is the proper thing to do, while attempting to obtain a gun when disqualified is very unwise and unlawful course of action.