Winchester NATO-Spec Military services Primers forty one are a similar primers used in the Lake Metropolis five.56mm ammunition. These primers are crafted to exacting specs for shot to shot consistency. All primers are regularly and rigorously analyzed for regularity winchester 41 primers and sensitivity at temperatures and circumstances much outside of the range of typical utilization. Winchester ensures meticulously-managed weights of primer mixtures, regularity in dimensions and high-quality, specific measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.