This National Match Spring Guide improves the consistency and smooth motion of the operating rod which helps reduce wear and increase rifle accuracy over the standard stamped GI guide. Produced to the same specifications as the military's national match rifles and enhanced by making them from one-solid piece of round 8620 tool steel with no welding to cause distortion. Each is case hardened to 40-45 HRc in an inert gas furnace to help maintain straightness and uniform hardness for long service. Finished with a corrosive resistant Mil. Spec. manganese phosphate (Parkerized). What makes this NM Spring Guide unique and more accurate is the precision alignment of the magazine catch to the guide shaft. This is achieved by turning the .344" diameter shaft from a larger diameter solid rod. The magazine catch is then precision CNC machined while being located from the guide shaft. Four flats are milled into .344 shaft body to reduce weight and friction between the spring which adds to the smooth action while precisely guiding the operating rod.