The greatest chance of racking failure probably is operator error. That is probably increased by stress as we know in every domain of human performance. It can be mitigated by training and practice under appropriate stress. David is well known to wield a wicked shotgun.
On the other hand, even the best fall to stress. Even top level competitors step up to line and futz it up.
As far as sound effects - I prefer:
Yoohoo, I have a gun and I've called the police.
As compared to:
Yoohoo, I'm racking my gun now and unloading it a touch.
BG - what did you say - I can't hear. Could you do that again?
OK - rack, rack.
Racking a chambered gun to make a sound as a tactic - love it.
That's why some nice FOF training that entails actual interaction with folks is an added nuance to sheer competition with no such interaction and a focus on gun mechanics as compared to the interactive gestalt.
This thread will never die!