I've had assisted knives confiscated on the basis that they're switchblades in the eyes of customs. I've had one OTF make it through from China, and all my others were bought from JB at Roadside Imports in the US - he strips them down and sends the parts in two or three different packets. That's the only surefire way to get past the knock.

I wouldn't advise it, as if they catch you more than once, I'm pretty sure you end up on some sort of list.