to the people saying you shouldnt shoot a double in concrete because you may hurt your knee... hmmm your in a sf with a dude whos willing to kick punch elbow soccer kick you, in the face, as hard as he can, and you worry about your knee hurting a bit... for fuck sakes, you are in a fight, yeah your probably going to hurt something, if it wasnt possible to shoot a double, then rugby players whouldnt exist. Yeah back to the old rugby thing, and just before anyone claims that rugby isnt played on concrete, you never been in a rugby field from a small club in a 3rd world country. its not as hard as concrete, but its pretty damn close...