Winchester NATO-Spec Army Primers 41 are the identical primers used in the Lake Metropolis 5.56mm ammunition. These primers are developed to exacting specs for shot to shot regularity. All primers are consistently and rigorously examined for consistency and sensitivity winchester 41 primers at temperatures and situations far further than the choice of typical utilization. Winchester ensures very carefully-controlled weights of primer mixtures, regularity in dimension and quality, precise measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.