Winchester NATO-Spec Army Primers forty one are the identical primers used in the Lake Metropolis five.56mm ammunition. These primers are crafted to exacting technical specs for shot to shot consistency. All primers are continuously and rigorously analyzed for regularity and sensitivity at temperatures and situations far further than the number of standard usage. Winchester ensures cautiously-managed weights of primer mixtures, consistency in measurement and top quality, exact measurements and tolerances for anvil heights and steadiness in extremes of temperatures winchester 41 primers and humidity.