Winchester NATO-Spec Armed forces Primers forty one are precisely the same primers Employed in the Lake City 5.56mm ammunition. These primers are built to exacting specs for shot to shot regularity. All primers are frequently and rigorously tested for consistency and sensitivity at temperatures and situations significantly further winchester 41 primers than the selection of standard utilization. Winchester ensures diligently-managed weights of primer mixtures, regularity in sizing and quality, precise measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.