Ork Big Gunz
You can also find out how I painted the Krew.
As for the gun that will be undercoated black. I do like the Big Gunz models that have been produced for the Orks, I don't like the lists that all the Big Gunz have to be the same (though tactically I know that is better). I already have a Kannon so was pleasantly surprised when my mother in law for my birthday gave me a Zapp Gun. It was easy to put together, though no instructions where to put the extra bitz, so they could be in the right place, more likely they are in the wrong place...
It comes with two krew, but in reality you need more than two as they die very easily at which point the gun becomes useless.
I now have a battery of three Kannon
This is a picture of them in action (or inaction as I should say as they didn't do too well).