From the projects page: This was my first [successful] attempt at building a custom pilot valve. It's similar to my first "compact" air cannon, the LAW I but 6" shorter and 30% lighter courtesy of the internal valve.

If the embed doesn't work for you, the video is also on youtube.

I'll get to the internals and build process.

But first some eye candy ;)

I love the sleek profile of this cannon.

Most of the things I build have that cobbled-together IED look, which is just fine with me. But I actually put some time into the appearance of this one and I've got to say it turned out damn sexy.

For ergonomics the butt should be bit lower, but keeping the recoil on-axis makes it alot more manageable.

Here's the concept diagram for the valve.

I had a long explanation of how it works here, but it's alot more intuitive to show in animation form.

(high pressure areas are highlighted in red, arrows represent air movement)

The idea kind of sat in my mind for a couple of years until I got bored one summer and built this prototype out of 2" pvc.

I don't have any bench machining tools at home, so I had to get creative with some of the components. More on that later.