A circuit breaker includes a frame, at least one conductor supported by the frame, and a breaker mechanism supported by the frame and including a trip bar assembly that actuates the breaker mechanism. The circuit breaker also includes a magnetic armature assembly including an armature plate configured to move responsive to a current in the at least one conductor and an elongate link member (e.g., a rod) coupling the armature plate to the trip bar and having at least one flanged portion retained in at least one keyed slot in at least one of the armature plate and the trip bar assembly. The elongate link member may have a narrowed portion sized to allow passage of the link member through a narrowed portion of the at least one keyed slot to facilitate engagement of the at least one flanged portion in the at least one keyed slot.