The guns on the decimator just look silly tiny. Been looking for something out of a model kit that would look legit and bad ass. Anyone know of anything good?

Shapeways has guns used on the new Battlestar Galactica (or if you have the model just use one of them).

Or you can take the turret off the YT2400 and proudly proclaim your over-compensating issues (just mount a single turret to the top...remove the lower one altogether).

1/700 scale ships have a nifty little 76mm gun that is in a dome (google the FFG-7 class to see what it looks like) Its just a tad larger than the Deci-gun.

Bandai also makes a mini-line of Space Battleship Yamato (Starblazers) ships. EBay "starblazers" under models and kits. Look for the 6-15 dollar kits and your find some ships with nifty turrets.

Hope this helps.

GW lascannons?