These 5.45x39mm cartridges feature clear-burning Berdan primers, Complete Metallic Jacket (FMJ) projectiles, and cost-saving metal casings which are coated with a light-weight film of polymer. The polymer coating guards the metal circumstances from rust even though in storage but additionally serves as being a buffer between casings and chamber partitions; https://tacticalrounds.com/product-category/handgun-ammo-for-sale/45-gap-ammo/