Gadsden is right.
On Dean Speir's site (thegunzone.com ) this is covered in a graphic detail.
Basically, the douchebags at Olympic arms made the OA-93 pistol chambered in 7.62 x 39.
Then BATFE went "BUH! GUH! WUH! PISTOL THAT FIRES 7.62 x 39 OMFG what should we do oh now we gonna getta banna all the chinese steel core ammunition cause its armor piercing bweeee!" Then WHAM- no more cheap 7.62 x 39. Gone. No more imports. An entire class of ammunition, banned from import, overnight.
Numerous industry people WARNED Olympic arms about the obvious repercussions of their firearm... (that it would trigger an ammo import ban on 7.62 x 39) but Olympic ignored them and showed the thing at SHOT, BATFE smelled it, and that's all she wrote. Now, from what I've been told... Olympic never actually sold one of these things, but BATFE considered it to be a solicitation at that point of an actual product, so that was enough to irritate them.
This is very similar to the reason why, despite obvious legality, nobody is going to sell a Saiga with a 20 round drum mag
hanging out the bottom of it, at least not as a package. They don't want the whole thing to get administratively turned into an NFA DD classification- because of the dumb sporting purposes clause, another hidden danger.
-Mike