<(O.o)> Pretty interesting, because of Japanese gun laws, when they hold a 'quickdraw' competition they have to use a blank or air soft type gun.
This video with Howard Darby is interesting to see how in Japan they can still have fun without breaking gun laws.
YouTube Video Placeholder
A lot of those quick draw performers use rice shells.
Basically, you take a brass casing, drill out the flash hole, press a magnum primer in and fill the brass casing with dry rice and glue a paper was over it. The primer is enough to blast the rice out and pop balloons.
Basically sleight of hand. Most of the bigger names in quick drawing use actual bullets though.