Partial Neck Sizing with Collet Die

If you want to resize just a part of the neck, find a washer at your local hardware store the has an inner diameter large enough to fit over the case, and an outer diameter large enough so that it contact the collet sleeve that protrudes from the bottom of the die.  Slide this washer over the case after the case has been inserted into the shell plate.  Now when the ram is raised, you can still close the collet by applying force at the top of the stroke, but the case will not go up as far into the collet, and the neck will be sized less an amount equal to the thickness of the washer.