Winchester NATO-Spec Military Primers 41 are the exact same primers used in the Lake City 5.56mm ammunition. These primers are crafted to exacting specs for shot to shot regularity. All primers are consistently and rigorously examined for consistency and sensitivity at temperatures and problems significantly over and above the array of ordinary usage. Winchester winchester 41 primers ensures diligently-managed weights of primer mixtures, regularity in measurement and top quality, exact measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.