A power tool that tensions metal locking ties. The power tool includes a base with a drive mechanism and a tool head mounted to the base. The tool head includes a tension mechanism, a gripper assembly secured to the tension mechanism, and a tool nose. The tension mechanism includes a lead screw secured to an electric driver in the base and a lead nut attached to the lead screw. The gripper assembly includes a gripper housing secured to the lead nut. As the lead screw rotates, the lead nut moves along the lead screw pulling the gripper housing toward the base of the tool to tension the metal locking tie.