Winchester NATO-Spec Military Primers 41 are exactly the same primers Utilized in the Lake Town five.56mm ammunition. These primers are developed to exacting technical specs for shot to shot regularity. All primers are continually and rigorously tested for consistency and sensitivity at temperatures winchester 41 primers and ailments considerably beyond the variety of ordinary use. Winchester guarantees cautiously-controlled weights of primer mixtures, consistency in dimension and good quality, exact measurements and tolerances for anvil heights and security in extremes of temperatures and humidity.