A gas spring for forming equipment, comprising: a casing with an axially extending side wall, an open end, a transversely extending closed end wall axially spaced from the open end, and a pressure chamber defined in part by the side and end walls to receive a gas under pressure; a bearing assembly received in the casing; a piston rod slidably received in the bearing assembly for reciprocation between extended and retracted positions; a piston rod seal received in the casing generally axially between the bearing assembly and the open end of the casing; a piston retainer received in the casing and separate from and normally carried by the piston rod adjacent an end of the piston rod received in the casing and normally having at least a portion thereof extending circumferentially continuously around the piston rod; and characterized by a deforming member in the casing adjacent to the closed end wall of the casing, and having at least two circumferentially spaced apart legs projecting generally axially toward the retainer and underlying and at least slightly spaced from the retainer when the piston rod is forced into the pressure chamber to the maximum extent of its design intended normal operating retracted position of the piston rod; and wherein the retainer is configured to engage the legs and to be plastically deformed when the piston rod is forced into the casing into an overtravel position beyond its design intended maximum retracted position; and the deformed retainer is configured to engage the bearing assembly and to be fractured and separated from the piston rod after such overtravel and when the piston rod returns to its extended position. a casing with an axially extending side wall, an open end, a transversely extending closed end wall axially spaced from the open end, and a pressure chamber defined in part by the side and end walls to receive a gas under pressure; a bearing assembly received in the casing; a piston rod slidably received in the bearing assembly for reciprocation between extended and retracted positions; a piston rod seal received in the casing generally axially between the bearing assembly and the open end of the casing; a piston retainer received in the casing and separate from and normally carried by the piston rod adjacent an end of the piston rod received in the casing and normally having at least a portion thereof extending circumferentially continuously around the piston rod; and characterized by a deforming member in the casing adjacent to the closed end wall of the casing, and having at least two circumferentially spaced apart legs projecting generally axially toward the retainer and underlying and at least slightly spaced from the retainer when the piston rod is forced into the pressure chamber to the maximum extent of its design intended normal operating retracted position of the piston rod; and wherein the retainer is configured to engage the legs and to be plastically deformed when the piston rod is forced into the casing into an overtravel position beyond its design intended maximum retracted position; and the deformed retainer is configured to engage the bearing assembly and to be fractured and separated from the piston rod after such overtravel and when the piston rod returns to its extended position.