Winchester NATO-Spec Navy Primers forty one are precisely the same primers Employed in the Lake City 5.56mm ammunition. These primers are created to exacting technical specs 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 high-quality, specific measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.