Winchester NATO-Spec Navy Primers forty one are precisely the same primers used in the Lake City 5.56mm ammunition. These primers are created to exacting technical specs for shot to shot regularity. All primers are continuously and rigorously tested for consistency and sensitivity at temperatures and problems considerably further than the selection of standard utilization. Winchester ensures meticulously-managed weights of primer mixtures, winchester 41 primers consistency in measurement and excellent, exact measurements and tolerances for anvil heights and security in extremes of temperatures and humidity.