Winchester NATO-Spec Military Primers 41 are the identical primers Employed in the Lake City 5.56mm ammunition. These primers are crafted to exacting specifications for shot to shot consistency. All primers are regularly and rigorously analyzed for regularity and sensitivity at temperatures and circumstances much outside of the range of regular use. Winchester assures carefully-controlled weights of primer mixtures, regularity in size and good winchester 41 primers quality, exact measurements and tolerances for anvil heights and security in extremes of temperatures and humidity.