I was taught by my instructor to shoot for the pelvis when unexpectedly attacked at bad-breath distance with gun or knife.
His rationale was that a draw followed by holding the pistol in retention at the hip, canted a few degrees away from the mid-body, naturally permits placing shots on the pelvis more quickly than any other target, while protecting the pistol from a grab. The hits are expected to inhibit the BGs mobility, particularly if bone is shattered, permitting getting out of range of a knife, and reducing the ability of a BG with a gun from firing accurately, ESPECIALLY if you sidestep off the X while executing the maneuver.
I have practiced this quite a bit, and the shots naturally go where expected. If the BG does not fall, one can probably run, or step aside and progress into the Zipper.
A bad-breath distance attack does not offer much in the way of options (unless you are H2H capable), so while pelvic shots are not infallible in stopping the threat, they may be the best option available, after which you may have the choice of running, or placing shots elsewhere.
This was taught me by an instructor who customarily carries a .38 and who taught me while using a 9mm, so he evidently thought these calibers were enough gun. In a previous thread on this subject, there was outright skepticism that these calibers would reliably do enough damage to be effective, and I concede that a heavier one would be preferable to shatter pelvic bone.
However, I think it is important to bear in mind that this defense is designed to get the all important first hit under difficult circumstances, and a pelvic shot is the best chance of doing so in the circumstances, as that is where the pistol initially points when drawn. It also provides time and space for further evasion. It is not designed primarily to attain a one or two shot absolute stop, which is in any case uncertain with this and other points of aim.
The zipper has been promoted as an effective defense because it permits placing multiple shots on target as soon as the gun leaves the holster and on it's way to COM and aimed fire without losing any time (with practice). It is a natural progression from the retention shots I described. Just remember to MOVE as you shoot!
"It is an absolute must, IMHO, to be able to make [uninterrupted] hits all the way throughout your draw stroke.....one handed or two. .... and zipper them up[wards] "
Sweatnbullets
Also:
http://www.defensivecarry.com/vbull...s-battle-concealed-handgun-permit-holder.html post 29 & after. (Great thread throughout).
C