Keep a copy of the TSA regs and specific airline rules you fly on your person.
Put a trigger or cable lock on the gun.
Make sure the case cannot be opened or allow your hand even partially able to reach inside even though the gun wouldn’t come out.
I put a padlock thru all the holes on the case so it is completely secure.
You won’t have any problems.
DO NOT USE THE SMALL TSA RED LOCKS WITH A THIN CABLE AND ALLOWS TSA TO ACCESS WITH A MASTER KEY. TSA WANTS YOU TO BE THEONLY PERSON TO ACCESS THE CASE.
My case worked fine and I didn't have to cable lock the gun. I had both United's regs and TSA regs with me. They were the same. My case only needs one lock, but has a steel round bar that goes through 4 buckles. The ticket agent thought it needed two locks even tough the regs don't say that and TSA was fine with it.
In Billings I was right next to the TSA agent as he went over the case. Even helping him move the case around. Some places just aren't as uptight as others.
