Winchester NATO-Spec Navy Primers forty one are the exact same primers used in the Lake City 5.56mm ammunition. These primers are crafted to exacting specifications for shot to shot consistency. All primers are regularly and rigorously analyzed for regularity and sensitivity at temperatures and circumstances much outside of the winchester 41 primers range of typical utilization. Winchester ensures thoroughly-managed weights of primer mixtures, regularity in dimensions and quality, specific measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.