Winchester NATO-Spec Armed service Primers 41 are the same primers Employed in the Lake City 5.56mm ammunition. These primers are created to exacting requirements for shot to shot consistency. All primers are regularly and rigorously examined for consistency and sensitivity at temperatures and situations significantly outside of the number of ordinary use. Winchester assures carefully-managed weights of primer mixtures, consistency in sizing and winchester 41 primers excellent, precise measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.