A spring-loaded reciprocable stylet holder assembly includes a cap; a hollow body element partially nested within and reciprocable a major part of its length into the cap; a spring urging the body element outwardly of the cap; and a stylet supported at one end by the cap and extending through and beyond...http://www.google.com.au/patents/US5531678?utm_source=gb-gplus-sharePatent US5531678 - Method of using a spring-loaded reciprocable stylet holder to eject a T-fastener
