Derek,
You are witnessing the vagueries (sp) of the wonderful "mate" between the Head and Pak of an E series combo. You can close this gap by getting the reflector to go further forward into the sealing O-ring which will then allow the LE to go in further. As long as the battery tube contacts the rear of the LE prior to the tube locking against the head, you are good to go. Now if you go to put this head on another tube and the LE is too far in, you will not make a ground contact and no light will come forth.
The head should never come completely against the body if you are to make a good ground contact. SF has made a concession to this lately with their E series lamps with some sprung tabs that will contact the battery tube and then compress to allow for a tight head to shoulder mate. The Aleph system is based on the older set where you would target for a .005" - .010" gap between the head and the shoulder.
Realistically, provided the O-ring is far enough covered to provide a bore seal, you are good to go.
I don't know if this helps or if I have confused the issue more. /ubbthreads/images/graemlins/icon3.gif
