This has been my focus of late in pneumatic technology.  I simply got tired of working with that rat's nest of wires and batteries.  Batteries will eventually die, and will instantly die if you leave the batteries on.  With this new design, I can fire a shot at the push of a button.  A solenoid valve operates on a couple of basic principles that allows this new design to work. 

When the gun is pressurized, the air enters the side of the valve and leaks over the diaphragm and then attempts to exit the valve's other side.  The pressure above the diaphragm seals the exit opening.  When the top chamber is depressurized, the diaphragm springs up and allows the air to exit. 

 

Under normal circumstances, it is the electricity actuated solenoid that depressurizes the top chamber.  This solenoid requires 3 9-volt batteries.  All the solenoid does is act like a valve.  So for my purposes, I intend to screw in a push-button  valve.

The single push-button valve is made by attaching a button that releases air pressure out the side when depressed.

This was the next step in my experiment is to try this on more complex guns.  My bazooka may no longer require that enormous battery box and pedal any more.  The valves will be connected with a hose and then joined at a push-button valve at a common junction.  This should be completed in the near future.