So what’s better than a battery gun? A full auto pneumatic battery gun of course! [ukilliheal], decided to build one of these, and show us the results in his video after the break. After turning the gun on, this contraption shoots at a pretty impressive rate of fire (although, apparently not as fast as some of his other experiments). Apparently batteries can do a pretty fair amount of damage to a cardboard target as shown around 1:20. [ukilliheal] apparently thinks this is pretty hilarious, but we wouldn’t want to be on the other end of this device!
Although details on this build are fairly slim in this video, [ukilliheal's] other videos should provide some clues, especially those where he explains how to make a full auto paintball gun. If the same technique is used, a piston reloads the chamber using a homemade valve that releases pressure when it gets too high. Electronics could also be used, but keeping everything mechanical will allow for the batteries to be used solely as ammuntion.
If full-auto guns aren’t your thing, why not check out this bolt-action miniature pneumatic spud gun!