Abstract: An automatically and semiautomatically unjamming nail selection device, designed particularly for machines riveting footwear heel seats onto corresponding heels. The device has a nail tank or magazine coupled with a rotary chamber equipped with units designed to lift the nails and drop them onto a chute having a number of raceways which join with corresponding guides leading to a mobile combshaped selector moving to-and-fro in a perpendicular direction relative to the nail feed direction. The selector is designed to select such nails and deliver them to a distributor moving to-and-fro parallel to the selector and having feeding ducts leading to the utilization outlet. The selector is integral with an arm controlled by a first fluid dynamic actuator which determines its to-and-fro elastic motion, and the distributor is connected--through a rigid coupling--to another arm which is, in turn, shifted elastically to-and-fro by a further fluid dynamic actuator.