Kentucky laws are the most lenient. In Kentucky, people don't need a permit to purchase a gun, but one is needed to carry a concealed weapon. To be approved, a person must be at least 21-years-old, a Kentucky resident for at least six months, and haven't been convicted of certain crimes.
Indiana also doesn't require permits to purchase guns. However, one is needed for carrying a gun in public. In order to qualify, applicants have to be 18-years-old or older, and cannot have been convicted of a drug, alcohol or violent crime.
The state of Illinois is stricter. People do need a permit to purchase a gun. They also have to be at least 21-years-old and pass a background check to be approved. There's also a waiting period for purchasing guns that ranges between one to three days. Also, carrying a concealed weapon in Illinois is prohibited entirely.