During disassembly of a spent perforating-gun tool string, an employee attempted to carry the setting tool (designed to set a plug in the well) section from the external stands into the trailer for breakdown. When he lifted the setting tool in the vertical position, he placed his right hand over and into the open end of the sleeve. At that point, the internal mandrel shifted further up to the open end. His right middle fingertip was pinched by the mandrel and the set-screw opening at the end of the sleeve, amputating the distal phalanx.