Winchester NATO-Spec Army Primers forty one are the identical primers Utilized in the Lake Metropolis five.56mm ammunition. These primers are developed to exacting specs for shot to shot consistency. All primers are consistently and rigorously examined for consistency and sensitivity at temperatures and circumstances far beyond the range of normal utilization. Winchester ensures very carefully-managed weights of primer mixtures, consistency winchester 41 primers in size and quality, exact measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.