Winchester NATO-Spec Military services Primers forty one are the exact same primers used in the Lake City 5.56mm ammunition. These primers are crafted to exacting specifications for shot to shot consistency. All primers are consistently and rigorously analyzed for regularity and sensitivity at temperatures and winchester 41 primers conditions much over and above the number of regular usage. Winchester guarantees meticulously-controlled weights of primer mixtures, consistency in measurement and high-quality, specific measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.