Sounds kinda like a post driver if I have the correct mental picture. Did you find it more efficient, less tiring, etc. compared to just swinging a maul? A nice 8#er can get after it pretty well (especially if a partner is setting the rounds).
There's an image of it
here. I don't get the feeling that a great deal of thought went into its design. The wedge should ideally be fatter with lightly concave faces: we buried it a few times without popping the wood apart. It's also too short (I had to bend at the knees quite a bit to be able to ram it home), and too light (many hard blows required). It's a neat idea, but needs to be optimized. As is, a maul is more effective as you can just let gravity do most of the work. It's nice that you can't miss with this thing (close calls with a maul glancing off stuff are a real heart-stopper!) but... efficient, it is not.
<img src="/ubbthreads/images/graemlins/frown.gif" alt="" />