I've had a sore experience with NW, went outbound from LAX with a pistol and ammo and then on return from International Falls, was where I hit the snag. Almost got stranded in MN thanks to inconsistent enforcement of their own firearm policies. I live 15 min away from LAX, I could have run home and gotten another lock box and still have made my flight.

Instead I had to repack my whole bag in front of the rest of the flight (it was a puddle jumper) and the rest of the flight gave me the dirtiest looks.

Then there's TSA who wanted me to remove the cable lock on my pistol so they could "swab for explosives".