Winchester NATO-Spec Army Primers forty one are precisely the same primers used in the Lake City 5.56mm ammunition. These primers are crafted to exacting specs for shot to shot consistency. All primers are regularly and rigorously winchester 41 primers analyzed for regularity and sensitivity at temperatures and circumstances significantly outside of the range of typical utilization. Winchester ensures diligently-managed weights of primer mixtures, regularity in sizing and high quality, precise measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.