Here is the engine in front view, for scale.  It is a reasonably heavy engine, and has a very scale look and feel to it, especially when it fires.
 
 
 
 
 

Here is a quarter view of the completed engine.  Francis has quite a kick, at about 50 yards it left a reasonable bruise on my unarmored leg with a rock made from 6 tennis balls.  In tests, at that range, it has been able to reliably and repeatably deliver payload to the target area, regardless of the mass of the payload (tests used 1 to 8 ball 'rocks').
 

I will hopefully have some downloadable AVI files on the net in the near future of Francis in use.