First I was about to write:
"Nice work, only the aft gun looks like it's floating in the air, unless there's some tarpaulin (or similar) hanging on the railings and covering the gun's base. "
But then I made a closer look:
And would say that at this moment it doesn't qualify as anything more than a very-early-stage-WIP.
Besides the artifacts, many of the "details" seem to be simply a leftover of the source drawing