Winchester NATO-Spec Armed forces Primers 41 are the exact same primers used in the Lake Town 5.56mm ammunition. These primers are built to exacting technical specs for shot to shot regularity. All primers are continuously and rigorously analyzed for regularity and sensitivity at temperatures and conditions far outside of the variety of typical utilization. Winchester ensures carefully-managed weights of primer mixtures, regularity in measurement and quality, precise measurements and tolerances for anvil heights and balance in extremes of temperatures and winchester 41 primers humidity.