I read elsewhere in the forum that it cannot be done on a C2 body.
If the body was bored for 18650,the "waist" where the grip rings sit
will be very thin .... might snap off.
EDIT found the thread, look here, Post #140
http://www.candlepowerforums.com/vb/showthread.php?t=199849&page=5
Thanks! That does make since now that I think about it.
C2 up for sale.....NOT!
How about a 17650?