4 years ago, not really knowing what airsoft was, I brought back from France a KWA M9 in my luggages. Not one problem. I was lucky. Thought now knowing a lot more about laws and such, I wouldn't take any chance. Then again, I'm a very careful person.
What I'm trying to say is if you try ( i do not condone this act), and shit goes wrong, assume. If you're not capable of that, then don't try; simple as that.