Winchester NATO-Spec Armed service Primers forty one are the identical primers Employed in the Lake Town five.56mm ammunition. These primers are created to exacting specifications for shot to shot regularity. All primers are consistently and rigorously examined for consistency and sensitivity at temperatures and problems considerably beyond the choice of normal use. Winchester ensures thoroughly-controlled weights of primer mixtures, regularity in dimensions and excellent, precise measurements and tolerances for anvil heights and stability in extremes of temperatures winchester 41 primers and humidity.