I've never seen the need to replace that spring so I've never tried. I can't tell if it's just a press fit into the grip, or if it's molded in during manufacture. It does go all the way through to the underside. If you can get a replacement (call S&W, they may send you one, or tell you it's not available as a replacement part which would indicate that it's part of the frame). If you end up with a replacement part it, then I'd try pulling/driving the old one out from the bottom side.