Winchester NATO-Spec Military services Primers 41 are the exact same primers Utilized in the Lake City 5.56mm ammunition. These primers are crafted to exacting specs for shot to shot consistency. All primers are continually and rigorously tested for regularity and sensitivity at temperatures and disorders far further than the array of usual utilization. Winchester assures very carefully-managed weights of primer mixtures, consistency in size and winchester 41 primers high-quality, precise measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.