Winchester NATO-Spec Military services Primers forty one are a similar primers used in the Lake City 5.56mm ammunition. These primers are designed to exacting specifications for shot to shot consistency. All primers are continually and rigorously examined for consistency and sensitivity at temperatures and ailments considerably beyond the array of standard utilization. Winchester ensures thoroughly-managed weights of primer mixtures, regularity in dimensions and high-quality, specific winchester 41 primers measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.