Oh, nobody is accusing you of complaining man, it's called "feedback" and I welcome it.
Say, how much exactly space is left when you screw back the retaining ring?
I always like to leave about 0.1-0.2mm space left (about that much short to threaded all the way), because, if for any reason the host is 0.1mm longer - boom, your heatsink will rattle around and not have a good electrical connection.
So I always like to leave tolerances for host factory deviations. Just to be on the safe side.
I do not understand what do you mean by "main shaft of the sink was little small"?