This is true 5.56x45mm mil-spec, new, unfired, heavy duty brass with that is recent production with a Lake City headstamp. It is the same brass supplied to our fighting forces in Iraq and Afghanistan and offers outstanding performance in AR-15 type rifles. We made a special buy on a limited supply and it will not last long. Cases should be sized, chamfered and deburred before loading. With this brass, there is no primer crimp to remove.