An electro-mechanical actuator in an aircraft brake may include a ball nut piston, and endcap coupled to the ball nut piston, a retaining ring coupled to the endcap, and a puck secured within the endcap. The puck may be permanently retained within the retaining ring. The retaining ring may be a split ring which is installed around a base of the puck. The puck may be inserted within a single-piece retaining ring, and the retaining ring may be bent over a base of the puck.