Currently your only choice is the Saiga series. Sometimes you can find a USAS-12 on GunBroker, but it's a DD and you'll pay out the nose
Valtro makes/made a magazine fed shotgun, but I've never been able to find anyone who imports it or even has one.
In pump guns, the Monolith P-12 had a lot of potential and was scheduled for production in 2009, but it's been 'delayed until the political climate stabilizes' aka: we won't tool up until we are certain our mega-dollars aren't going to be made useless with a ban.
I put 70-rounds through a USAS-12 earlier this week, had all the kick of a 5.56
