Twin-Synchronized-Anit-Aircraft-Auto-Cannons.
I decided my forward deck (on the nose) definately needs some light AA weapons, and so I started building these AC's.
I started with the barrels and several rings in two different diameters
Here you can see the muzzle breaks (without the cuts) and the first set of rings
Since these central rings need a larger diameter, I slipped a second, larger ring over them
Then the rear barrel "root"
More rings on top of the root, and done were the barrels
Then I built the actual gun housing - rather straight forward