Winchester NATO-Spec Army Primers forty one are the exact same primers Utilized in the Lake Metropolis 5.56mm ammunition. These primers are constructed to exacting specs for shot to shot consistency. All primers are regularly and rigorously tested for consistency and sensitivity at temperatures and circumstances much further than the array of ordinary use. Winchester ensures very carefully-controlled weights of primer mixtures, regularity in measurement and top quality, precise measurements winchester 41 primers and tolerances for anvil heights and stability in extremes of temperatures and humidity.