I work for Tsa, each airport is slightly different in how they handle checked firearms. I can't speak for your home airport, but here's my advice based on my knowledge. Firearms must be unloaded and placed in a hard sided case that is locked. If you are traveling with ammunition, it must be secured however, it can be in the case with the firearm. Magazines, manufacturers packaging, and bullet boxes that are designed to hold, carry, or store ammunition securely can be used, I've seen altoid tins, shoe boxes. And large ammo cans used. These are not acceptable. Locks are up to you. Any lock thAt you want to use is up to your discretion, Tsa has a set of master keys designed for sentry locks. They will have. TSA ###. Printed on them. However, if you use a lock that is not Designated as such. Be prepared to be called back to the counter with the key. Should your rifle case need to be opened. Also, a firearm declaration form has to be filled out and included inside the case, this is available from your airline rep. Any other questions feel free to ask, I'll watch this thread.