I also saw this on Future Weapons and it was pretty cool. Pretty much all stainless, so it was maintenance free. Recoil was minimal. It was select fire (full auto/semi auto). It would fire a variety of ammo, including a grenade with stabilizer fins that would give it an effective range of several hundred yards.
They can be mounted on vehicles like Hummers & Bradly's and fired remotely from inside the vehicle.
Even with the Class 3 License, you still couldn't own this because they're manufactured after the enactment of the Gun Owners Protection Act of 1986. In addition, even if they were to come out with a semi-auto only mode, the BATAF could declare it a NFA Destructive Device just like the USAS-12, Streetsweeper, and Striker-12.