I did these a little time ago, and I am only getting around to getting them on my blog today. No respecting ork warboss worth his salt would leave home, without 9 of these bad boys.
So the conversions themselves are straightforward to do, as you see in the pictures. I find using bits of plastic card to lengthen the barrels, gives them a little bit more of a natural look, and makes it easier to identify them on the tabletop.
Must admit I'm quite pleased how they are working out, so if you have any
questions you know what to do.