This is An ORIGINAL dust cover (mortise cover) spring Winchester 1873. AND 1876 it is held in place by a screw (wp607-a or the original screw is w162-a wop) in a rectangular cut out on the front of the dust cover rail. This little spring sticks up out of the rail and puts tension on the underside of the dust cover to help keep it closed (after you push the dust cover back shut with your finger) and to keep it from going back and forth when tipping the rifle. Your dust cover has to be removed in order to see/replace this little guy. The new dust cover springs are part wp607-a.
