About a year after 9-11 I was going through security at the airport here in Montana. I had a coat on that I used hunting that fall, and unbeknown to me there was a spent 300 WSM case in the pocket (completely fired, empty, and with punched primer). But TSA had a minor meltdown - they pulled me out of line, did a pat-down, and got a sheriff standing there involved. Looking the sheriff in the eye, I asked all those surrounding me if any of them knew the first thing about firearms. I explained it was left-over from elk hunting that fall, and that was how an empty brass cylinder inadvertently came to be in my pocket. I said, "this is Montana, we hunt elk." The Sheriff was sympathetic, but the TSA acted like I'd just attempted another 9-11 lol. Ultimately they confiscated the "evidence," and let me on the flight. A couple weeks later I got a letter from the FBI detailing my infraction...
I have spent time as an Airport Manager. What you experienced there was absolutely a left wing TSA staff.
Every TSA station in the country finds both fired and unfired rounds in hunting backpacks. It happens ALL THE TIME. I guarantee that airport you visited has a large bowl of bullets in the back room. As well as knives and other contraband.