Winchester NATO-Spec Military Primers 41 are the same primers Utilized in the Lake Metropolis five.56mm ammunition. These primers are constructed to exacting requirements for shot to shot regularity. All primers are continuously and rigorously examined for consistency and sensitivity at temperatures and ailments considerably past the variety of ordinary use. Winchester assures cautiously-controlled weights of primer mixtures, consistency in dimension and top quality, exact measurements and tolerances for anvil heights winchester 41 primers and balance in extremes of temperatures and humidity.