Flying from MSY to LAS on Spirit went mostly smooth. I had one handgun, a KelTec PR57, in a Pelican V100 lockbox inside another piece of luggage.
The airline agent asked if the locks were TSA-approved. I thought it might turn into an issue, but it didn’t. I told her they were not TSA locks and explained that they don’t have to be. She said TSA would call if they needed anything, I agreed, and that was the end of it.
When I landed, my bag came out on the carousel like normal. Everything was secure, and I was on my way.