Winchester NATO-Spec Army Primers forty one are the same primers Employed in the Lake Town five.56mm ammunition. These primers are developed to exacting requirements for shot to shot regularity. All primers are continually and rigorously examined for consistency and sensitivity at temperatures and problems significantly outside of the range of typical usage. Winchester guarantees very carefully-controlled weights of primer mixtures, regularity in measurement and good quality, precise measurements winchester 41 primers and tolerances for anvil heights and stability in extremes of temperatures and humidity.