[tcostell]

I doubt anyone has done a study on it but there is mountains of empircal evidence. I don't know a single gun owner who diesn't have a story about a relative driving away intruders just by chambering a round.

Anyone?

[Gilbo_3]

while racking a pump gun may drive away the 'honest' BG, it is a loss of cover/initiative to the hard core thug...

that said, Id imagine a few bladders have emptied on the way back to the entrypoint upon the sound of chambering a round...