Feel's like someone's first attempt at drawing millitary equipment.
It's a good attempt, much better than I could do, but the guns are a tad stubby. If you try to aim for roughly 1:1 gun length to turret depth you can't go wrong (unless we're talking AA guns...).

EDIT:
Looking again at Gascogne's official art, it looks like her gun:turret ratio is more like 4:5 rather than 1:1.
Still, the artist has more of a 3:5 ratio going on here which really does look stubby.