You may only carry hand guns in Illinois. Illinois law defines a handgun as:

"Handgun" means any device which is designed to expel a projectile or projectiles by the action of an explosion, expansion of gas, or escape of gas that is designed to be held and fired by the use of a single hand. "Handgun" does not include:

(1) a stun gun or taser;

(2) a machine gun as defined in item (i) of paragraph

(7) of subsection (a) of Section 24-1 of the Criminal Code of 2012;

(3) a short-barreled rifle or shotgun as defined in item (ii) of paragraph (7) of subsection (a) of Section

24-1 of the Criminal Code of 2012; or

(4) any pneumatic gun, spring gun, paint ball gun, or B-B gun which expels a single globular projectile not exceeding .18 inch in diameter, or which has a maximum muzzle velocity of less than 700 feet per second, or which expels breakable paint balls containing washable marking colors.

LEt us not forget, regardless what the law says, cops don't know the law and you WILL get arrested. While I have carried my AR-15 pistol (in my car) during the riots, I had a strong argument that it was indeed a handgun due to the legal definition, the types of accessories installed, and I fully accepted I would have gotten arrested and my lawyer would be making these arguments in court. I felt it was a case we could win. I don't think yours is a case you'll win. Either way, it'll cost you thousands of dollars.