Go hang out on some saiga web sites and watch them argue about it all day long. Even the ATF is not consistent in what they tell people in letters, and of course why would you expect them to be?
Where the debate seems to be is the definition of fixed mag. Some feel if your gun does not have points 1,2 or 3 listed by DJ then #4 with 10 round mags should be ok.
The end result is 10 round mags like I have for my Saiga, are just not available to civilians right now because the middle man is to affraid to sell it to you. To clarify, I am not an LEO, but a few years ago the mags were being sold to civillians.
So while it is legal to manufacutre a post ban mag that holds 10 rounds, no one is sure if you can hang one on a semi-auto shotgun if you are not LEO.
I think that is why Knoxx hs not designed a mag for a semi yet. Only pump guns. Things will be better after 9/14/04!