I've read that only about 180 or 190 SPAS-15 shotguns were imported to the United States before the importation ceased to be legal. Does anyone here know what, specifically, it violated to be so affected? Is it still illegal to import one?
Not sure what makes them banned, whether by name or by features, however they are still illegal to import. If someone started making them state-side in the same configuration though, I think they'd be perfectly legal.
The relevant statute you're looking for is 18 USC 925(d)(3)
The Attorney General shall authorize a firearm or ammunition to be imported or brought into the United States or any possession thereof if the firearm or ammunition—
(3) is of a type that does not fall within the definition of a firearm as defined in section 5845(a) of the Internal Revenue Code of 1986 and is generally recognized as particularly suitable for or readily adaptable to sporting purposes, excluding surplus military firearms, except in any case where the Attorney General has not authorized the importation of the firearm pursuant to this paragraph, it shall be unlawful to import any frame, receiver, or barrel of such firearm which would be prohibited if assembled;
Thus, all that was really necessary was to ban its importation was a finding by the AG that the SPAS was not particularly suitable for sporting purposes.
Yup, that would be it. What sucks is that Franchi actually called the series "Sporting Purpose Automatic Shotgun" for that exact reason. Guess it didn't help that much.