There are numerous reports of 'failure to stop' shootings coming from both Afghanistan and Iraq. (Both with thier AK and our M-16).
The Strategy of modern warfare has been to cause as many wounded enemy combatants as possible to tie up enemy resources and personal. Unfortunately the current enemy has very little fear of death, willing to die to achieve the goal. Our Military has been looking at a larger caliber, heavier bullet to inflict more serious injury. In other words, ‘You gotta kill them pricks to stop’m’.
Depending on who you think you might wind up fighting with in the future, you might want more gun than you've been planning on.
As a Peace Officer I've seen enough instances of wounded Bad Guys completeing an assault after being shot to know that you better have enough gun.