Winchester NATO-Spec Army Primers forty one are a similar primers used in the Lake Metropolis five.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 than the selection of standard utilization. Winchester ensures diligently-managed weights of primer mixtures, regularity in sizing and quality, precise measurements and winchester 41 primers tolerances for anvil heights and stability in extremes of temperatures and humidity.