(720 ILCS 5/2-7.5)
Sec. 2-7.5. "Firearm". Except as otherwise provided in a specific Section, "firearm" means any device, by whatever name known, which is designed to expel a projectile or projectiles by the action of an explosion, expansion of gas or escape of gas; excluding, however:
(1) 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;
(1.1) any pneumatic gun, spring gun, paint ball gun, or
B-B gun which expels breakable paint balls containing washable marking colors;
(2) any device used exclusively for signaling or safety
and required or recommended by the United States Coast Guard or the Interstate Commerce Commission;
(3) any device used exclusively for the firing of stud
cartridges, explosive rivets, or similar industrial ammunition; and
(4) an antique firearm (other than a machine-gun) which, although designed as a weapon, the Illinois State Police finds by reason of the date of its manufacture, value, design, and other characteristics is primarily a collector's item and is not likely to be used as a weapon.