Durus: struwwelpeter nailed the answer to your question above, in spades. Even in states with an amended Castle Doctrine -- so called "stand your ground" or "shoot first" (as the antis love to call them) states, a zealous prosecutor could turn your justifiable shooting into something going before a Grand Jury based on specific intent to kill rather than provide for lawful self defense!
BTW: For serious SHTF I prefer a revolver. 30 years of range time on active duty and reserves with 1911's and M9's leaves me a bit wary of automatics.
Ever experienced an extruded primer that hangs up on the revolver backplate? I have. A gunsmith had to detail strip it to clear the hung round. Had that happened in a confrontation my revolver would have become a paperweight. I've only experienced that particular issue once in my life -- that's about 40 years of shooting experience. That's once too many for me. I use revolvers for teaching only. I've been a certified instructor for 22 + years. Any weapon I choose to carry for the purposes of self defense has to be 100% reliable in it's essence. That of course doesn't include a faulty magazine or even operator error. But in any case, I have to be able to clear a jam in an emergency and put the piece back into service to defend my life or the lives of others. I can always do that with a semi auto. I have not yet run into a jam that I couldn't rapidly clear, again in that 40 year span, if I do my part.