I just finished rendering something that might help out anyone in trouble with the tip. Now, just a few explanations:

The two pieces (six sided) which the rec wire attaches to is better described as a "tall nut" it's like a regular nut but not flat. Home Depot has it. Each end of the wire is glued inside the thread of each of these pieces. Each of the piecs can be either glued or attached via a screw (preffered method). The bracket around the tube tip can be bought or made by shaping a strip of aluminum. The screw that tightens that bracket goes with the "tall nut" Thread must match. In between the bracket and the tall nut is a piece of aluminum that is shaped by cutting out an inverse trapezoid and folding down the flaps 45 degrees. Piece should look like the picture above.

Hope this helps...
CPU64

P.S. The clear tube should roll free inside tip. This piece I just drew above
will be flat to the left with the tip extended. When the tip is inside, the
tube will naturally rotate and the piece will be now 45 degrees. Check Peter's
gun on the cover of GBII and you'll know what I mean. My gun does the same
thing.