I checked a Winchester shotgun in case on AA from PHX to DFW this summer. Oddly, the TA asked me to open the case and clear it (show her that the weapon was not loaded). I was a bit surprised as I didn't think some random, female (don't mean to be sexist there) agent would know what the hell she was looking at.

Anyway, I unlocked the case, pulled out the shotgun at the ticket counter, with people in line behind me, and pumped that sucker as loud as I could. She actually jumped a bit.

Anyway, it went through TSA locked and they just scanned it through the machine. Came out in DFW in the spot where golf clubs come out.

No problems.