http://video.google.com/videoplay?do...2984714729812#
If a paintball marker can do it Im sure it would work even better for an airsoft gun.
It would be cool to at least have a choice to hook up an external tank on a GBBR. Personaly I wouldnt mind as long as the hose ran out from the back of the gun somewhere. Then I could just have it running along with my sling.