Winchester NATO-Spec Military Primers forty one are the identical primers Utilized in the Lake Town 5.56mm ammunition. These primers are constructed to exacting requirements for shot to shot regularity. All primers are frequently and rigorously tested for regularity and sensitivity at temperatures and situations considerably outside of the choice of standard usage. Winchester ensures diligently-managed weights of primer mixtures, consistency in dimension and good quality, exact measurements and tolerances for anvil heights and winchester 41 primers security in extremes of temperatures and humidity.