This spud gun was built by my brother and me, we think that all of the other combustion potato guns were wimpy!.so we made our own. It is 12 feet long, 4 feet tall, and weighs 54lbs. It shoots on average 500 yards despite the wind. It has onboard propane and air tanks for quick reloading, as well as breech loading, and removable “shells” to make reloading quicker. It is triple propane injected, has a metering tube to get the exact amount required (4.3%) and the air tank flushes out the “used” air after each shot. An electronic control panel controls the valves for air and propane, the ignition will soon be upgraded to a stun gun, as of now it is still a dual spark BBQ grill igniter.
The blue is the chamber, and the red is the barrel, and the three green objects are electronic valves. The igniter is recessed in the handle.
Here you can see the gray electronic control box, the black propane tank, and the small red manual air pump.
Inside shot of the breech load. The middle pvc pipe is the rear of the barrel, it is what I call the “shell”.
Picture of the shell removed.