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 regularity. All primers are frequently and rigorously analyzed for regularity and sensitivity at temperatures winchester 41 primers and situations much outside of the range of typical utilization. Winchester ensures diligently-managed weights of primer mixtures, regularity in sizing and quality, specific measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.