Winchester NATO-Spec Military services Primers forty one are a similar primers used in the Lake Metropolis 5.56mm ammunition. These primers are built to exacting specs for shot to shot consistency. All primers are regularly and rigorously analyzed for consistency and sensitivity at temperatures and circumstances significantly further than the selection of typical utilization. Winchester ensures thoroughly-managed weights of primer mixtures, winchester 41 primers regularity in dimensions and high-quality, specific measurements and tolerances for anvil heights and balance in extremes of temperatures and humidity.