Winchester NATO-Spec Military Primers forty one are exactly the same primers Utilized in the Lake Metropolis five.56mm ammunition. These primers are developed to exacting requirements for shot to shot regularity. All primers are continuously and rigorously tested for consistency and sensitivity winchester 41 primers at temperatures and ailments considerably beyond the variety of usual use. Winchester assures carefully-controlled weights of primer mixtures, regularity in size and high quality, precise measurements and tolerances for anvil heights and balance in extremes of temperatures and humidity.