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