Actually, if you read through this thread:
http://forums.thedentedhelmet.com/showthread.php?t=4965
You will find that the agreed upon consensus is that the placement of the clamps versus the length of the barrel does not match up and that the scope Has to be mounted to the Flash Tube.
THere is some debate as to whether the front mounting bracket was positioned that way for asthetic reasons or because it further helped to secure the flash tube into place.
Bottom line... Front Bracket connected to flash tube.