These five.45x39mm cartridges element cleanse-burning Berdan primers, Total Metal Jacket (FMJ) projectiles, and cost-conserving steel casings which might be coated with a lightweight movie of polymer. The polymer coating safeguards the steel situations from rust while in storage but in addition serves as a buffer amongst casings and chamber partitions; https://tacticalrounds.com/product-tag/9mm-luger-ammunition/