Winchester NATO-Spec Armed service Primers 41 are exactly the same primers Employed in the Lake City 5.56mm ammunition. These primers are created to exacting specs for shot to shot consistency. All primers are continuously and rigorously examined for regularity and sensitivity at temperatures and problems far outside of the variety of standard use. Winchester ensures thoroughly-controlled weights of primer mixtures, regularity in sizing and quality, specific measurements and tolerances for anvil heights and balance in extremes of temperatures winchester 41 primers and humidity.