Winchester NATO-Spec Armed forces Primers forty one are the exact same primers Employed in the Lake Town five.56mm ammunition. These primers are constructed to exacting specifications for shot to shot consistency. All primers are continuously and rigorously analyzed for regularity and sensitivity at temperatures and disorders significantly further than the array of normal usage. Winchester ensures carefully-controlled weights of primer mixtures, consistency in sizing and excellent, precise measurements and tolerances for anvil heights and stability winchester 41 primers in extremes of temperatures and humidity.