Well, I'd like to build this :
Just use an existing gun and import your 3D model into it. You would only be changing the look of it nothing else. I mean they don't really work, the barrels are not even hollow.:rotfl:.
didn't even see that myself !!
Take the new S3D and look at a double barrel Jap gun, in the .dat file there is a label and 3D model and nothing else, it's the sim file that makes it act like a gun. NO PROBLEM!! In the sim you place the barrels at specific locations so they look right then add the effects like smoke and shell to use and so on. Shouldn't be a problem. Send me a 3d model I'll put it on a ship and shoot the Jyunsen B. :rotfl:.
It might have to wait a week cause I'm going to France on saturday or sooner if I find the time 
Seriously it shouldn't be a problem, you make a 3D model of a sub and make it work, a gun should be easy.
:rotfl:
The only thing you might need to change is the location of the barrels and they give you x,y,z. If you need the barrel to tip up I think that is a rotation in the .dat for the barrel. But, I don't think I would try to built from a painting, if you could find a picture.
Also, you don't need to put it in the gunsradar.dat, In fact making ships I have to take guns OUT of the gunsradar.dat. Just take out a gun that is similar to what you are making, add your 3D, remap IDs and change the name. Then use that new name in the UPCData or UPCDataGE stuff for weapons and upgrade packs and put the guns .dat,.sim.zon in the subparts.
Peabody