I joined bladeforums today and asked in my first post. (In my second post I gave wise advice to a mother who is looking for a knife as a present for her son's graduation from USMC boot camp - <wiseacre/> ) In my two answers so far it has been established that the thumb stud does in fact screw out. I emailed Al Mar to try to find out the diameter of the hole, which I suppose has to be a good match to the wave insert.

I will update with what I find out.