Ok,
I just got back yesterday from traveling to Michigan via Chicago Ill. and through Indiana.
I put my firearm in a
Center Of Mass Central box and put that into my checked on baggage. I located it in the middle between my clothes so as to conceal it from any baggage handlers who may otherwise 'feel' it if it were in an outside pocket. I packed 50 rounds of ammo (in its original box) and two empty mags into a small nylon zipper pouch.
Declaring it at SF took about 20 minutes. They took me to a room next to the check in area where they x-rayed it before clearing it. The guy did not even open my luggage. He said they only get a couple a month.
I declared my firearm at Chicago Midway airport and after the lady finished rolling her eyes she had me go over to a TSA agent who was set up at a table off to the side in the baggage check in area. He proceeded to wipe everything down to test for explosives and he did open up my baggage to inspect the firearm. It took about 10 minutes.
All in all it went well. Much easier than I thought it would be.