Winchester NATO-Spec Navy Primers forty one are a similar primers Utilized in the Lake Metropolis five.56mm ammunition. These primers are built to exacting specs for shot to shot consistency. All primers are consistently and rigorously analyzed for regularity and sensitivity at temperatures and conditions much over and above the number of regular usage. Winchester guarantees very carefully-controlled weights of primer mixtures, consistency in measurement and excellent, specific measurements and tolerances for anvil heights and security in extremes of temperatures winchester 41 primers and humidity.