A firearm improvement taking the form of a mechanical dynamo installed in an automatic firearm. Several components either replace certain parts of the firearm or are added to the firearm. In conjunction with the operation of the firearm, the components generate electric energy which is then stored in a capacitor, battery, or other element for the storage of electric energy, or supply power to a battery recharging unit attached to the firearm. The electric energy contained in the storage component, or used to recharge the batteries placed in the recharging unit, may be used at a later time as a back-up power supply for electronic components attached to or incorporated into the firearm, such as red-dot or reflex sights, laser sighting equipment, or night vision equipment.