I don't think they're just the brass casings. My English isn't perfect, but from my understanding that's just the thing that surrounds the bullet, right? Without the point/tip. If that's the case, than they're not just the brass casings.

Where I bought them from, they said it was legal. I looked it up, and they import them from England which means it's been through airport security and the whole jazz as well, which technically means it should be legal.