M&P 15-22 Stainless Steel Firing Pin. Using our in house CNC Swiss turning centers the firing pins are machined from domestic 17-4 Stainless Steel then Heat Treated to a Rc44 to Rc47. We machine the firing pin from Stainless to help eliminate internal corrosion issues and improve reliability. Heat treating the firing pins to H900 condition gives them high strength and great toughness. Made in the USA!! Length 2.123 inches Nose diameter 0.089