Winchester NATO-Spec Military services Primers forty one are the exact same primers Employed in the Lake City 5.56mm ammunition. These primers are created to exacting specifications for shot to shot consistency. All primers are consistently and rigorously analyzed winchester 41 primers for regularity and sensitivity at temperatures and circumstances significantly outside of the variety of ordinary usage. Winchester guarantees very carefully-controlled weights of primer mixtures, consistency in measurement and excellent, specific measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.