Winchester NATO-Spec Armed forces Primers forty one are precisely the same primers Employed in the Lake City 5.56mm ammunition. These primers are crafted to exacting technical specs for shot to shot consistency. All primers are winchester 41 primers consistently and rigorously analyzed for regularity and sensitivity at temperatures and conditions much over and above the number of regular usage. Winchester guarantees meticulously-controlled weights of primer mixtures, consistency in measurement and excellent, specific measurements and tolerances for anvil heights and balance in extremes of temperatures and humidity.