Holy bullcrap Batman!
Nothing signals danger quite like the unmistakable sound of racking a shell into the chamber of a shotgun.
O, I get it. You're talking about when the music get really dramatic and the hero says some catchy one liner and punctuates by racking a shell in his 12 gauge?
In reality, while racking a shell in your chamber for dramatic effect works well in the movies and stands a good chance of scaring an intruder, it's tactically foolish. It provides vital intel to the intruder that you do not possess about him/them, namely, your location and that you are armed. Intel is the difference between victory and a sucking chest wound on the battlefield, and anywhere you stand a decent chance of exchanging gunfire is officially a battlefield.
Even if you do go with a shotgun, you're far better off just keeping the thing loaded and leaving Steven Segal in Hollywood.
Except maybe a rattlesnake. Definite deterrant value there, but i don't want rattlesnakes in my house.
About the only thing in your post that makes sense.
For close quarters, especially in your home, you don't want to spray and pray.
Yeah, but who said anything about spray and pray? Not me. I even specified "aimed" fire. Why is it someone always assumes an advantage in capacity equates to a lack of marksmanship?
From a spray and pray point of view, 80+ whatever-sized round balls directed with a bead sight en masse qualifies a lot more than individually aimed hammer pairs from a rifle. It's simple probability. Every projectile has to be accounted for, and more projectiles stand a higher risk of collateral damage than less projectiles aimed individually with the same care.
Twelve shots of panic-fired jacketed .308s is formidable, but a miss is flying far and fast to who knows where.
Thus the reason you aim. And for the record, I don't know what you're insinuating, but there is no reason using a rifle for self-defense should result in any more panic-ed fire than a shotgun. The rifle is just more accurate, and gives the user more control over what gets a hole in it, and where that hole is.
A single shotgun shell at close range sends an ounce or more (an ounce is 437.5 grains, people, compared to 125gr 9mm, or 225gr .45, or 55gr 5.56) of lead in nice tight patterns - regardless of choke or shot size - inside 10 yards. Place that in the COM and the BG is down hard. Yes, energy is exponential to velocity and only linear to mass, but mass is a constant that cannot be ignored. Heavy things simply take longer to stop. Besides, if you're defending your family, do you want a little .3" hole (made with 2500ft/lbs but with a very high chance of pass-thru) or a gnarly 2" hole (made with 2000 ft/lbs that disperses all its energy in the wound) in the BG chest?
Yes, but each pellet has comparatively little mass, and thus, little momentum. A single 00 buck pellet weighs about the same as a single 5.56 round, or a little less, and its greater diameter means it has a lower sectional density. This means it sheds velocity faster and penetrates less. And that isn't necessarily a good thing.
The velocities produces by a shotgun are closer to those produced by handguns than they are to those produced by rifles. This means that the shotgun lacks the velocity to cause damage to organs beyond the immediate path of the projectile(s). So each buckshot pellet is carving a pencil-sized hole, with little or no damage occurring beyond the permanent wound cavity produced by the individual projectile. In effect, you're emptying a .32 caliber mouse gun in the general direction of the enemy and relying on the cumulative effects of these rounds to be more than the sum of its parts.
By comparison, you have a 168 gr Hornady Amax leaving an 18 inch M1A Scout at over 2500 fps. At, this velocity, shock forces produced by the projectile are violent enough to permanently tear and bruise vital tissue for several inches beyond the immediate path of the bullet. Plus, by virtue of its construction, this bullet fragments violently upon impact, losing nearly half of its mass to this effect. At its widest point, the crush cavity of this round, achieved somewhere around 6 inches of penetration, is over 5 inches in diameter. The projectile eventually comes to halt with barely over half its original mass and about twice its orignal diameter after penetrating about 16 inches of tissue--ideal for defensive application. This means that a single expanding .308 round possesses over 70% of the tissue displacement and wound cavitation of your average 12 gauge buckshot round. And because it has less recoil, and at least twice the capacity, the user can operate hammer pairs at in-house distances with a high-probability (at least as high as all your pellets striking the target at the same distance) of both rounds impacting on target, and he can still engage ten times without reloading once. Meaning the shotgun has the advantage in actual application in neither firepower nor terminal effect, when the rifle is employed in this manner.
Even assuming your energy dump theory holds water (and it doesn't), when and if the rifle bullet exits the attacker's body, it's already "dumped" more energy into the target than the 12 gauge round even possess.
And none of this comes at the expense of conventional advantages held by rifles, such as range and accuracy. A rifle carbine is at least as handy indoors as a shotgun, and even a 7.62mm battle rifle such as a FAL or M1A is going to be light enough that no adult capable of handy 12 gauge recoil should notice it, esp given the advantages associated with that extra weight.
I think Pete is correct - bird shot doesn't over-penetrate secondary or tertiary walls, but certainly still packs a wallop at short distance. The Pincus video is interesting, if not purely scientific. The beauty of lead shot is that at close range, it acts similar to a solid projectile but as it spreads or encounters resistance, it separates and acts like individual light projectiles, spending its energy faster hence the lower penetration at distance.
Penetration is your friend. Those who research these things (mostly by shooting things and analyzing the results) know this. Too little penetration is far more dangerous than too much penetration. Too little penetration gets you stabbed or shot (then the BG moves on to your family). Too much penetration might result in the bullet killing or injuring an innocent 3rd party, or their property. I'll take "will" vs "might" odds any day of the week.
Shallow, superficial wounds, such as those created by birdshot (at any range), are unreliable stoppers. Without damaging vital organs or the CNS, only pain response and the mental response of getting shot stand to stop an attacker. Even without other mind-altering substances, these responses are likely to be dulled by the adrenaline and other chemicals created in duress by the body. The only way to reliably stop an attacker barring a hit to the CNS, is by blood loss and damage to vital organs. This requires the round to penetrate to the vital organs, regardless of clothing encountered, or shot angle presented, and regardless of what skeletal-muscular obstacles the round encounters. This is why the FBI has a mandatory 12 inch of penetration rule, even after penetrating heavy clothing, or other obstacles. They prefer 14 to 16 inches, and so do I. Nearly half of all Americans are overweight, and 1/3 of them are obese. That means the chances of your round having to penetrate more than the 6 to 8 inches provided by birdshot is very high.
I've seen 6 and 7 1/2 shot fail to stop ground squirrels from perfectly centered patterns out of an extra-full turkey choke in my 870 Wingmaster at ranges I have in my house far too many times to trust birdshot on anything larger than a rabbit. Beyond 30 to 40 feet, exit wounds are the exception rather than the rule even on these 1.5 pound varmints.
Don't get me wrong - i like all my guns for their various uses. But my rifles are all hunting tools, powerful and accurate at long-range. For HD, in the middle of the night, I'd start with the shotgun. Just point and shoot. And repeat as necessary.
"Just point and shoot"? Now who is spraying and praying?
If, by your own admission, the shot acts like a single projectile at close range, that would seem to indicate that it still has to be aimed like a single projectile. And indeed, that is the case.
http://ammo.ar15.com/project/Self_Defense_Ammo_FAQ/index.htm#.308
Well it all depends on the situation.