Here's my model of the AA gun. I'll try to the post a little test animation clip soon to show how it moves.
I made a couple of design changes, most important one is that I've opted for 2 sets of barrels instead on a single set. Main reason was that's it's more technically correct, otherwise you won't need to have 2 ammo magazines ( the 2 big cilinders at the back). Besides, the more guns, the cooler the gun !! :D
2nd major change is that I've replaced the cheesy anime 'fins'at the rear and replaced them with a radar assembly and some more support modules.