I had 1 experience in this situation. I was on the way home from the gun show with a brand new shotgun in a box with "MOSSBERG" printed on it. the fare nazi's asked what was in the box, and I said a Shotgun.... He just said OK and went on his way.
I have seen signs at the max stop near the expo ctr. regarding thier policy... but I can't remember it... I do know that when I called a couple years ago they said it was at the drivers discretion.
i like that... "HAY! HAY YOU! Whattyathinkyerdoin! What's in the BOX, huh? Think you can pull a fast one on ME? That box says MOSSBERG on it, you think I don't know what MOSSBERG MAKES??? So what's in the box, boyo?"
"A shotgun."
"Oh... well ok then."