Quote Originally Posted by irving2008 View Post
Yes, there's something that looks like a little centre in there.., here are some pics...
That's the one...

Screw the nose shut, it doesn't grip until the cutter is in place. Screw in a milling cutter until it hits the pin, open the nose slightly so you can screw the cutter in another quarter turn then tighten the nose.

Don't screw the cutter in too far, smaller sizes can shatter if not supported by the threads because the nut drives against them.