I have flown in and out of Atlanta with my firearm. Best advice ever given to me was there-don't use softsided luggage! With their plastic zippers it is easy to "pop" the zipper seam open-reach in grab stuff- then swipe the zipper back an forth and make it seem the luggage was never opened! The TSA agent that inspected my gun recommends hardsided luggage.
Here is how I transport my firearm when I fly-and yes I still use softsided luggage
I have a small lockable hardcase to store my gun in which goes inside my suitcase.
I use a flexible cable lock thru the gun to satisfy the unloaded requirement...
After they inspect the gun and I put the signed card in, I ALWAYS lock both the cases locks.
My particluar case has two carry handles-one on each side of the case halves which I use to to secure the case to my suitcase! Using another flexcable lock, I run/loop the cable thru and around the handles and since my suitcase has a steel frame I lock the cable to the frame.
And then I DO lock the suitcase also with the wimpy TSA approved lock.
It's faster to do it than type it.......
So a thief would have to pop the zipper, reach in thru all the clothes and find the case, pop the two locks on the small case, then he has to figure out how to either break the handles off or break the suitcase frame...without drawing attention to himself...and yes it could happen but this feels secured! (Or steal the whole bag.....)
So if you can secure it, go ahead and take it.