TexasCHLforum.com

Traveling through Chicago is legal under FOPA, since you are legal in both the origin and destination states.

The Illinois State Police has a whole bunch of web pages on their website on how to legally transport a firearm through IL under IL state law. IL requires the FOID, but the ISP states they recognize out-of-state CHL's as being equivalent to an FOID.

Flying into Chicago should not be a problem, since you are merely picking your checked bags up and leaving.

Federal law or not, I would be very nervous about checking the gun in at either O'Hare or Midway for the return. How many times have we seen news reports from previously-free states of someone arrested at airport check-in?

If it was me, I'd try to arrange an FFL in Gary IN or otherwise close to the IN-IL border that would mail mail my handgun back home on the return trip. An FFL can send in a medium flat rate box for $15 postage plus FFL fees. A lot cheaper than even one hour of a lawyer's time.