Winchester NATO-Spec Military 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 consistently and rigorously analyzed for regularity and sensitivity at temperatures and conditions much over and above the choice of normal usage. Winchester guarantees very carefully-controlled weights of primer mixtures, consistency in dimension and good quality, exact measurements winchester 41 primers and tolerances for anvil heights and security in extremes of temperatures and humidity.