Winchester NATO-Spec Navy Primers 41 are precisely the same primers Utilized in the Lake City 5.56mm ammunition. These primers are developed to exacting specs for shot to shot regularity. All primers are continually and rigorously analyzed for consistency and sensitivity at temperatures and ailments much further than the choice of standard use. Winchester guarantees diligently-controlled weights of primer winchester 41 primers mixtures, consistency in size and high quality, specific measurements and tolerances for anvil heights and steadiness in extremes of temperatures and humidity.