That sound is actually the sound of the overhead cover supports ringing to the shock wave - weird isn't it?
Don't worry, the next one will have the steel target in it - I don't lie about what I can shoot. Here's a video proof of how I roll.
http://www.youtube.com/watch?v=Zx-rQYeHTug
Had a few people critique that one too...have yet to see them post up video of them doing it themselves.
Music is a VERY pro gun group called HogJaw, who did the original song at the range they and their buddies were shooting at that day. They're also a local group.
http://www.youtube.com/watch?v=82h2hyM4DTM