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