Well, I went and found the full information about trying to exploit this ruling.
apparently Google searching skills is by population ratio - is a superhuman trait.
I am not going to link it, out of respect however it should be noted that the 407-500 fps classification is by no means fool proof. this is the pinky toe wedged in the door frame letting SOME
(it will be a while for most GBBs - I think)
Ill leave this alone now with the highlight of the explanation (why its still risky, and should leave the hassle with the retailers.)
This is still not a bullet-proof method of importation, as enforcement and interpretation of the laws are subject to the individual officer actually inspecting a particular vehicle or package. Many officers may not actually be adequately informed of all the latest minor legal changes to the laws