Winchester NATO-Spec Armed service Primers 41 are a similar primers Utilized in the Lake Metropolis five.56mm ammunition. These primers are constructed to exacting requirements for shot to shot regularity. All primers are constantly and rigorously tested for consistency and sensitivity at temperatures and problems considerably beyond the array of usual use. Winchester assures carefully-managed weights of primer winchester 41 primers mixtures, regularity in size and high quality, precise measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.