As long as it's in a box, and loose your OK. I travel with ammo in factory boxes. They don't really care if I had Hevi-shot or Federal shells in a Winchester box.
True Story...around about 2002, my ammo got pulled from my luggage. The TSA agent on site told me I couldn't fly with it because it was 12ga. I asked why that was a problem, because the shells were in a factory box, taped up I might add. And then he told me the reason. 8ga was the biggest ammo I could fly with.
I had to get a supervisor to clear it up the situation.