Many moons ago I used the same backpack for the range and an occasional business trip. I once showed up to CLT with a loaded 15 round G19 mag in a backpack pocket. I blissfully tried to go thru security and was busted of course. I was surprised to find out that after the rounds were confiscated TSA asked if I wanted the mag back. They gave me a form to fill out so they could mail the empty mag back to me. Sure enough a couple of weeks later I got the mag back. Not sure how the same situation would be handled today.