Warp said:
You arbitrarily set a seemingly-unrealistic limitation in order to create a scenario that best fits your argument.
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You also stipulated only one attacker/bad guy for your scenario.
I agree that if I am facing one, single, un-armoured attacker, a 12 gauge pump is quite good. But if they have armour, or they too have rifles, or there are more than one of them (VERY common)...I'm going to feel (and BE) a lot better off with the 5.56 carbine than the 12 gauge pump. Since I can't predict who or what I will face in the unlikely and unfortunate event of an intrusion, I choose the carbine to be kept ready.
And even if it's a single attacker, I still think I'm better off with the 5.56 carbine.
Are you just trying to argue at this point? 'cause I certainly wasn't. I have no particularly strong argument to make on this subject, other than saying that a 5.56 or a 12 gauge are each ballistically superior to a 9mm carbine, which is something of at least notable value to me in certain HD situations. Obviously (short of choosing a semi-automatic shotgun) you lose some rate of fire by moving to a shotgun. But, my intent was not to derail this thread into some debate about every little possible variable that could be debated on this subject. Granted, some of those considerations are important in the overall thread, but they weren't really within the scope of the point I was trying to illustrate.
My intended point remains, whether the example I used to illustrate it was arbitrary or not: a shotgun has a lot of power per round. Obviously I realize that there are other advantages to a semi-automatic, just as there are advantages/disadvantages to many other types of guns.
You would choose a 5.56 carbine for the threat of a single attacker, and that's perfectly fine, and based on sound logic. Personally, if I was waiting in an ambush position in a bedroom for what I believed was a single nighttime intruder (the manner of response I believe is the smart way to handle such a situation in many, but not all, cases), I'd probably reach for a shotgun. My neighbor drives an SUV, I drive a truck. Neither of us is "right", and neither of us is "wrong".
I'm not trying to tell you what to carry, and I'm not even trying to come up with a 'right' or 'wrong' choice. I'm just highlighting some options/features. I've used shotguns, handguns, and AR-15's professionally, and each has their advantage in certain situations. I've also had each of these available for home defense at one point or another (my bedroom currently features my CCW handgun and an AR-15 of carbine length). My one-shot example was merely to highlight where a shotgun does its best work. If you feel that you may have to face the threat of multiple intruders, longer distances, a likelihood of missing your first shot, opponents wearing body armor, or so on, there's plenty of argument for an AR-15 over any other manually fed weapon. If you need an affordable and simple weapon that has a huge amount of bad-guy anchoring capability, a shotgun isn't a bad choice.
I believe that many people are trying to equip their home for a situation in which they are planning around a threat of one attacker, who is quite often an unarmored burglar. This is also probably the most common threat I've seen in my career. Is it always possible that the threat is greater than they anticipated? Sure, it certainly is, but that wasn't really within the scope of my point. Anyway, I've yet to find myself in a situation (outside of work) where I felt that I was insufficiently armed with a 12 gauge shotgun... others obviously have.
Anyway, more to the original point of the thread, and with the caveat of saying that I'm talking of a situation falling well short of a Zombie Apocalypse, I would feel fine with either a 9mm carbine or a 5.56 rifle. I'd let the needs of the particular user dictate the decision in this case, and the most obvious difference I can point out between the two are:
1) .223/5.56 has more "stopping" power
2) 9mm will generally provide faster follow-up shots
3) 9mm will likely be more quiet (my 9mm carbine certainly is)
4) More parts, accessories, etc are available for the AR-15 platform.
5) The .223/5.56 will defeat most soft body armor.
I'm sure I missed quite a few points, and advantages/disadvantages to me may not be for someone else.