In a nosepiece/receiver assembly having a housing for receiving a part, a removable jaw mechanism that is mounted for pivotable movement against a biasing spring. The jaw member has a contoured surface for holding a part received by the nosepiece/receiver assembly when the jaw member is in a part holding position. The jaw member includes channel at one end for enabling the jaw member to pivot about a securing member of the assembly to a part releasing position. The jaw member may consist of either two cooperating movable jaws or one separate jaw. The jaw mechanism also includes a resilient biasing device for urging the jaw member into a part holding position. The biasing device is in contact with both the housing of the nosepiece/receiver assembly and the jaw member, with at least a portion of the resilient biasing device being external to the jaw member to allow easy replacement of the biasing device. The biasing device is positioned to minimize the chance of breakage of the jaw.