Illinois anything over .18 caliber is a firearm
This is partially true...it has to be over 700 fps as well. That was a change to the law a few years ago. So basically .177 has no restriction at all, anything larger has to be less than 700fps. It is stupid though since based on the law I cannot buy a Marauder in .22 from PA but I can buy a .50 dragon claw.
Brian