Winchester NATO-Spec Navy Primers forty one are precisely the same primers Employed in the Lake City 5.56mm ammunition. These primers are constructed to exacting requirements for shot to shot regularity. All primers are consistently winchester 41 primers and rigorously analyzed for regularity and sensitivity at temperatures and conditions much over and above the number of regular usage. Winchester guarantees meticulously-controlled weights of primer mixtures, consistency in measurement and excellent, specific measurements and tolerances for anvil heights and stability in extremes of temperatures and humidity.