This looks awesome—especially the colour pallette. I do have a question, though: A gun that big has a lot of recoil, but it doesn't look like there's much room in that turret for a gunner and a recoiling barrel. How does it work?
There's a bit more space than it looks like, or at least it's tailored to the problem. 
It can actually recoil most of the way back into the bustle. The turret holds two crew which sit to the sides. The gun is loaded from a hydraulic autoloader located beneath the turret ring. The overlapping of the breech at full recoil with the turret ring naturally limits maximum elevation, but this thing is pretty much direct fire only and relies on shell velocity to make the platform work.
It can actually recoil most of the way back into the bustle. The turret holds two crew which sit to the sides. The gun is loaded from a hydraulic autoloader located beneath the turret ring. The overlapping of the breech at full recoil with the turret ring naturally limits maximum elevation, but this thing is pretty much direct fire only and relies on shell velocity to make the platform work.