Make a decent post and that's alright! Looks cool, like one of those AA guns on ships during WWII. I sat in one a while back when I was on vacation near the ocean (of course).
Maybe have a seat and it rotates the whole seat thing. Like its a turret you get into, not a gun to man. Use a uh60mg gunner animation maybe.
But hey you're the addonmaker, not me.
PBR guns I heard somewhere that its only one gun firing real bullets, they both have muzzle flash for show. I think if you looks closely you can see only one stream of bullets.
Then again, I think they left two barrels out cause of the single gun per vehicle and to keep the PBR from mopping the floor with the EAST boats... Not sure though. :-\