Like mentioned above, locked in a hard sided case with a NON-TSA lock and declared at the check-in counter. On one or more occasions, I was invited into a private booth with a TSA agent and had to show them it was unloaded, so keep the key to the locked case on your person. I'm not sure what the rules are about ammo anymore, but I think I was prohibited from having any ammo in the case with the firearm and it had to be in a different checked bag. I've flown with firearms probably 3 times in my life and never had any issues. I have *heard* about horror stories, but never experienced one.