Winchester NATO-Spec Armed service 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 regularly and rigorously analyzed for regularity and sensitivity at temperatures and circumstances considerably past the variety of ordinary use. Winchester assures cautiously-controlled weights of primer mixtures, consistency in size winchester 41 primers and top quality, exact measurements and tolerances for anvil heights and balance in extremes of temperatures and humidity.