Rule 6. Choice of caliber vs magazine capacity. Refer to rule number one. You are still confused.
I dunno, caliber and mag capacity both tie in with shot placement. Bigger bullets give you a (very) slightly higher chance of nicking an artery, and have (very) slightly faster effect if they hit in a non-CNS vital area. But more shots = potentially more chances to place a shot that intersects the brain or spine. Of course, in the end it comes down to who landed an effective shot first, and in the majority of self-defense shootings things happen so fast that by the time you've burned through 5 or 6 rounds, it's over.
Hm, forget I said anything, then, I guess, you were right the first time.