there is also a really god bit about this in the one with a gun dvd.
make sure when u put your hand down it is BEHIND you, so that you are not putting any stress on it with the momentum your carrying into the bunker, it is merley an aid too helo you stabilize and get back up on your feet ASAP.
i would REALLY reccomend watching "one with a gun" dvd, its like £10 or something, goes through so much usefull info on sliding, snapshooting, breakout shooting, running and gunning, stancework, drills, diet, fitness.
good luck anyway.
tom