Winchester NATO-Spec Army Primers 41 are the identical primers Employed in the Lake City 5.56mm ammunition. These primers are designed to exacting specifications for shot to shot consistency. All primers are continually winchester 41 primers and rigorously examined for regularity and sensitivity at temperatures and conditions much over and above the range of regular utilization. Winchester ensures thoroughly-managed weights of primer mixtures, regularity in sizing and quality, precise measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.