Winchester NATO-Spec Navy Primers forty one are the exact same primers used in the Lake City 5.56mm ammunition. These primers are designed to exacting technical specs for shot to shot consistency. All primers are continually and rigorously examined for regularity and sensitivity at temperatures and disorders far past the choice of ordinary use. Winchester guarantees cautiously-controlled weights of primer mixtures, winchester 41 primers consistency in dimension and top quality, exact measurements and tolerances for anvil heights and balance in extremes of temperatures and humidity.