Originally Posted by THE DEADLY DOG
As far as I know mate it is 100% random. I also know if you shoot any particular leg too early it may close by the time it get's to the point you need it to be at. Actually had that happen to some guys I played with when they shot it by Gen 5 and it was closed by the time it made it to gen 4 / jugg.
Any idea why both feet are frequently closed during the Rain Fire step? I can look later, but maybe it's a case of only one foot is available betwen the three giant robots... very frustrating.