[Radoye]

What really intrests me is what effect the recoil would have from firing all those guns hock:

Better question is how the hell is that lower turret being kept in place - naval turrets like that were held by gravity alone.

As for the recoil - Italian Piaggio P.108A 4-engined heavy bomber variant was fitted with a 102mm cannon firing a 13kg shell for anti-shipping work. That's 4 inches, 28.6lbs.