I'm not a big fan of firearms, however things that can launch corks, ping-pong balls and larger past the speed of sound is simply brilliant.
DerpykV, your going to have to take some more shots with it and an (realtime) overview video.
nik282000, love how you can see the pressure wave build up and the disk break just before the ball touches it.
I'm assuming you've tried it with clear packing tape too? I've used it very well in the past. That with enough lighting, the ball painted black/white and the camera aimed as strait down the barrel as you dare would give give a very interesting shot indeed.