Abstract: A radially expandable endcap adapted for mounting upon a mandrel of a collet of a forming package winder. Other aspects of this invention include a collet and winder including the above endcap and method for winding strand using the same. Another aspect of the present invention is a collet having an expandable mandrel on at least a portion of a first end of the collet proximate an operator and distal to a second, opposite end of the collet mounted upon a support Other aspects of this invention are a winder including the above collet and a method for using the same.