Winchester NATO-Spec Military Primers 41 are exactly the same primers Employed in the Lake Town 5.56mm ammunition. These primers are created to exacting specifications for shot to shot consistency. All primers are consistently and rigorously analyzed for regularity and sensitivity at temperatures and conditions much outside of the range of regular winchester 41 primers 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.