Winchester NATO-Spec Navy Primers forty one are precisely the same primers Employed in the Lake City 5.56mm ammunition. These primers are designed to exacting specifications for shot to shot consistency. All primers are regularly and rigorously analyzed for regularity and sensitivity at temperatures and circumstances significantly further than the selection of standard use. Winchester assures winchester 41 primers carefully-controlled weights of primer mixtures, regularity in size and top quality, exact measurements and tolerances for anvil heights and balance in extremes of temperatures and humidity.