Winchester NATO-Spec Military services Primers 41 are the same primers Utilized in the Lake Metropolis five.56mm ammunition. These primers are constructed to exacting specs for shot to shot regularity. All primers are frequently and rigorously tested for consistency and sensitivity at temperatures and situations significantly further than the selection of standard utilization. Winchester ensures diligently-managed weights of primer mixtures, regularity in sizing and top quality, exact measurements and tolerances for anvil heights and balance in extremes of temperatures and winchester 41 primers humidity.