Winchester NATO-Spec Military services Primers forty one are the exact same primers Employed in the Lake Town five.56mm ammunition. These primers are developed to exacting requirements for shot to shot consistency. All primers are regularly and rigorously examined for consistency and sensitivity at temperatures and circumstances far beyond the selection of regular use. Winchester assures thoroughly-controlled weights of primer mixtures, winchester 41 primers regularity in measurement and top quality, specific measurements and tolerances for anvil heights and security in extremes of temperatures and humidity.