HOW IT WORKS
First, to know how it works, you have to know what it looks like (at least one version):
It works by putting a combustible material i.e. hair spray, right guard, WD-40, etc. into the
chamber and screwing the lid on. Next, you ignite it usually by means of a BBQ ignitor (or
other sparking/igniting device). What that does is build up pressure in the chamber and
the only way out (most of the time) is through the barrel.
Next, see a segment of animation I made showing how to load and fire the spudgun.