They used to have (maybe still do) gyroscope dampers for cameras, so that you can hand-hold a camera from an airplane or something and still get steady images. If you can find one, they have a convenient 1/4" tripod thread; I'm sure you could rig something up for a gun.
The auto-firing thing sounds like a real safety problem, not to mention the legalities. I'm very hesitant to allow electronics into guns, not for technical reasons but for legal reasons. I saw what happened to paintball when the electronic markers caught on. The definition of 'semi-auto' became very very grey, to say the least. An electronic trigger implies a switch. Everyone knows that switches bounce and need either electrical or software debouncing. The implementation of that algorithm leaves a whole lot to interpretation. Software is capable of detecting and queuing every switch bounce, and waiting until the action is ready to fire again and then immediately doing so as long as there is a trigger pull in the queue. It's very common in paintball software to do just that. Will the BATF consider each switch bounce 'a trigger activation'? Even with mechanical guns, there is always a delay between the trigger actuation and the firing of the gun. What happens when we can make that delay as long as we want via software?