Winchester NATO-Spec Armed service Primers forty one are the same primers Utilized in the Lake Town five.56mm ammunition. These primers are developed to exacting technical specs for shot to shot regularity. All primers are continually and rigorously examined for regularity and sensitivity at temperatures and conditions much over and above the range of typical utilization. Winchester ensures diligently-managed weights of primer mixtures, regularity in sizing winchester 41 primers and high quality, precise measurements and tolerances for anvil heights and balance in extremes of temperatures and humidity.