Here’s the file.
If you render it, it works fine, everything moves is sync, but when run in the game engine, two out of three times around, one of the smaller cylinders has this awkward vertex-stretching thing that looks like cheap m-bluring. I can’t tell if it’s bad parenting/grouping, or if something beyond my knowledge is going on.
When I play it frame by frame with my arrow keys, It looks fine, so I don’t think it’s the parenting. Please check it though.
If you’re wondering about the file, it’s going to be a chaingun, like the one from UT3.