My Hammerhead turret is a perhaps a little less direct.
A couple of images of WIP are in my
ToEG 2013 Colonial TauThe turret base is from a plastic Eldar support weapon.
The guns are square section brass rod and box section.
The smaller rod fits into the box section.
I am going to produce some Fusionheads using round section rod and pipe based on the same turret body. Shorter ones like on my crisis drones. There is a magnet in the bottom of the turret and a couple of staples in the body of the tank so that I can swap turrets whenever I want to.
I did find gluing short lengths of styrene rod using a plastic welding glue to be pretty effective. Used these as weapons for my Crisis Suits (same ToEG)