Winchester NATO-Spec Military Primers 41 are a similar primers Employed in the Lake Metropolis 5.56mm ammunition. These primers are designed to exacting technical specs for shot to shot consistency. All primers are regularly and rigorously tested for regularity and sensitivity at temperatures and ailments significantly over and above the number of ordinary usage. Winchester ensures very carefully-managed weights of winchester 41 primers primer mixtures, regularity in dimension and quality, precise measurements and tolerances for anvil heights and security in extremes of temperatures and humidity.