Airsoft Lab demonstrates a rapid firing VFC MCX Virtus AEG that uses a 7.4v Lipo battery. It's not an out-of-the box AEG as it has been upgraded with PERUN V2 Hybrid MOSFET, 13:1 Gears, Warhead Brushless motor, TopMax Airseal, and Maxx M4A HopUp Chamber. If you want a custom job you can contact them to discuss what you want.