There's a fair bit of bad advice in this thread.
The locks should be standard padlocks, key or combo, your choice. They can NOT be "TSA Approved" locks. You, and only you, retain control over access to the keys and case. It is illegal for TSA to open the case if you are not present. This is stated very clearly in the TSA regulations. Print out a copy of them, read them, and keep a copy with you in your carry on bag in case you need to reference it or politely inform a TSA/airline rep that they are wrong.
I recommend NOT flying Delta unless you have to. The guy that shot up Ft. lauderdale airport flew Delta, so as a response, Delta has gone overboard on security including zip tying all luggage containing firearms. It is illegal for an airline to mark any luggage containing a firearm, but guess what, only firearms get a zip tie. Do the math. I have had the smoothest and best experiences checking firearms on Southwest.
There's no point in bothering with chamber flags, removing bolts, or any other shenanigans to "prove" its unloaded. The only person who "checks" whether your firearm is unloaded are the actual ticket counter attendants. I have checked guns 30-40 times and literally never encountered a single agent who has given any indication that they know the first thing about firearms. Not one has ever inspected a chamber to confirm my claim of it being unloaded.
Mags can be loaded according to TSA regs, but some airlines (Delta, I think) prohibit it. Check with your airline. Print out their specific regulation sheet and bring it with you in your carry on bag. If you are flying with loaded mags, make sure you pack your case so the mags aren't lying directly on top of the magwell/chamber. Remember, an X ray shows a 2 dimensional image. It can look like the mag is inserted in the magwell on film, even though it's sitting in an entirely different compartment in your case.
Get a bright post it note and write your First name, last initial, and your cell number on it. I usually write something like "Please don't cut my locks, just call me: 123-867-5309. Thank You!" Use packing tape and tape the post-it to the outside of the case so that TSA can contact you. Some airports have a dedicated scanner for firearms. Other airports just send your bag into the regular queue. If your bag goes off down the regular conveyor belt, the smart move is to wait near the ticket counter for 10-15 minutes to ensure TSA doesn't have any questions or want to inspect something manually. If they do, they will call your cell that you have taped to the case. If they can't get in touch with you, they will cut the locks, inspect, and then just close your luggage and send it through unlocked. It's never happened to me, but a buddy had his locks cut with no notification and the bag transported unlocked. Two AICS magazines were missing at his destination.
TSA regs say 11 lbs of ammo, but I have never once had my ammo weighed. YMMV.
