Winchester NATO-Spec Armed forces Primers forty one are the exact same primers used in the Lake City 5.56mm ammunition. These primers are designed to exacting specifications for shot to shot consistency. All primers are consistently and rigorously examined for consistency and sensitivity at temperatures and ailments considerably beyond the array of winchester 41 primers standard utilization. Winchester guarantees meticulously-controlled weights of primer mixtures, regularity in sizing and quality, specific measurements and tolerances for anvil heights and security in extremes of temperatures and humidity.