I agonized over that ambiguity myself and ended up packing the weapon and two empty mags in the lockable pistol case. I took the cartridges and put them in a clear baggie so they could see what they were without having to handle them. No one even blinked other than to compliment me on my Colt Commander.
I am recommending putting the ammo back in an ammo box, either plastic or the original packaging, just to be sure.