You want a full auto backup than a pistol for your airsoft games? Get a mini-assault rifle instead. Mach Sakai reviews the Tokyo Marui AUG Mini AEG which is just too cute to look at. Powered by 4 Double A batteries and fires 0.12g BBs so its good for kids and for some indoor plinking such as inside your bedroom. Mach Sakai does the review for you to learn more: