Winchester NATO-Spec Armed forces Primers forty one are the exact same primers Employed in the Lake City 5.56mm ammunition. These primers are created to exacting technical specs for shot to shot consistency. All primers are continually and rigorously tested for consistency and sensitivity at temperatures and circumstances winchester 41 primers much over and above the number of ordinary use. Winchester ensures thoroughly-controlled weights of primer mixtures, consistency in sizing and quality, specific measurements and tolerances for anvil heights and balance in extremes of temperatures and humidity.