Winchester NATO-Spec Armed forces Primers forty one are the exact same primers Employed in the Lake City 5.56mm ammunition. These primers are crafted to exacting specifications for shot to shot consistency. All primers are regularly winchester 41 primers and rigorously analyzed for regularity and sensitivity at temperatures and circumstances much outside of the range of regular use. Winchester guarantees cautiously-controlled weights of primer mixtures, consistency in dimension and top quality, exact measurements and tolerances for anvil heights and security in extremes of temperatures and humidity.