Abstract: A split sleeve (96) is seated in a fastener hole (10) in the web (8) of a rail section (2). The tapered portion (26) of a mandrel (20) is firmly seated in the hole (10) inside the sleeve (96). A puller mechanism jaw (40) and a nosecap (78) are moved downwardly over the projecting rear end portion of the mandrel (20) to position the rear end portion in aligned U-shaped slots (50, 84) in the jaw (40) and nosecap (78). During the downward movement, guide surfaces (72) carried by the jaw (40) guide a chamfer (32) on the mandrel (20) into seating engagement with a tapered surface (56) on the jaw (40). The guide surfaces (72) may be formed by cylindrical pins (70) received into angled openings (58) in the jaw body. The front surface (88) of the nosecap (78) securely abuts the Web (8). With the mandrel ( 20) seated and the nosecap (78) abutting, the jaw (40) is moved rearwardly to pull the mandrel (20) through the hole (10) and cold expand the hole (10).