A plain round wire, yes, and it protrudes out over the corners of the
hex very slightly. As far as I can tell it is about 1/16" diameter.
The fingers resemble 6 flat wheel spokes which overlap each other at
the center of the hex-shaped hole. If you have the ram upside down and
are looking into the end of it you will see these spokes at the bottom
end of the hole. After taking a closer look, they don't seem to have
any springiness to them at all and apparently are there only to block
the upper end of the hole so that the tap holders won't go in too far.
I may be able to get a picture of the hole if it will help, though my
digital camera is not that good with extreme closeups.

Mike