Piston bore distortions in a sub-surface safety valve are reduced or eliminated when valve body is subjected to high working pressures. In one embodiment, a piston is disposed in a sleeve that is disposed in a piston bore. The bore can distort but the sleeve within will not distort to the point of losing sealing pressure around the piston. In another approach additional bore or bores are provided adjacent the piston bore to make the pin end of the connection for the valve housing more uniform in the region of the piston bore so that pressure loading does not result in sufficient distortion of the piston bore to lose the piston sealing relation in its bore.