Our military brass is sourced from U.S. Military installations. Considering that the majority of military weapons firing 7.62×51 brass are machine guns; yes – our brass is machine gun fired. Will this affect it’s performance? Possibly. A machine gun with an overly loose, worn out chamber has the potential to cause the brass to over-expand. When this happens, the brass, although resized using a small based die, will still refuse to case gauge or chamber properly. This is the case with all military brass sold on the market today. It takes only one armorer failing to properly identify these faulty weapons and pull the weapon from service to cause reloaders a bit of frustration.