Winchester NATO-Spec Military Primers 41 are a similar primers used in the Lake City 5.56mm ammunition. These primers are designed to exacting specifications for shot to shot regularity. All primers are frequently and rigorously analyzed for regularity and sensitivity at temperatures and circumstances much over and above the number winchester 41 primers of normal usage. Winchester guarantees cautiously-controlled weights of primer mixtures, consistency in size and high quality, precise measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.