Winchester NATO-Spec Armed forces Primers 41 are the identical primers Utilized in the Lake Metropolis 5.56mm ammunition. These primers are designed to exacting technical specs for shot to shot regularity. All primers are constantly and rigorously analyzed for regularity and sensitivity at temperatures and conditions far beyond the selection of regular use. Winchester guarantees diligently-controlled weights winchester 41 primers of primer mixtures, regularity in measurement and good quality, specific measurements and tolerances for anvil heights and security in extremes of temperatures and humidity.