A retaining pin for handling injection molded preforms includes a body including an internal body flow channel, and a plunger coupled to the body and movable relative to the body between advanced and retracted positions. The plunger includes an internal plunger flow channel. The plunger further includes a plunger abutment surface directed away from the body. The plunger is biased toward the advanced position and movable to the retracted position by engagement of the plunger abutment surface with an inner surface of a closed end of a preform when the preform and retaining pin are moved toward each other. The body flow channel and the plunger flow channel are in fluid communication when the plunger is in the retracted position. Fluid communication between the plunger flow channel and the body flow channel is inhibited when the plunger is in the advanced position.