In the home, #1 buck!
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12 Gauge Shotshell Ammunition
For personal defense and law enforcement applications, the International Wound Ballistics Association advocates number 1 buckshot as being superior to all other buckshot sizes.
Number 1 buck is the smallest diameter shot that reliably and consistently penetrates more than 12 inches of standard ordnance gelatin when fired at typical shotgun engagement distances. A standard 2 ¾-inch 12 gauge shotshell contains 16 pellets of #1 buck. The total combined cross sectional area of the 16 pellets is 1.13 square inches. Compared to the total combined cross sectional area of the nine pellets in a standard #00 (double-aught) buck shotshell (0.77 square inches), the # 1 buck shotshell has the capacity to produce over 30 percent more potentially effective wound trauma.
In all shotshell loads, number 1 buckshot produces more potentially effective wound trauma than either #00 or #000 buck. In addition, number 1 buck is less likely to over-penetrate and exit an attacker's body.
For home defense applications a standard velocity 2 ¾-inch #1 buck shotshell (16 pellet payload) from Federal, Remington or Winchester is your best choice. We feel the Federal Classic 2 ¾-inch #1 buck load (F127) is slightly better than the same loads offered by Remington and Winchester. The Federal shotshell uses both a plastic shot cup and granulated plastic shot buffer to minimize post-ignition pellet deformation, whereas the Remington and Winchester loads do not.
Second best choice is Winchester's 2 ¾-inch Magnum #1 buck shotshell, which is loaded with 20 pieces of copper-plated, buffered, hardened lead #1 buckshot. For those of you who are concerned about a tight shot pattern, this shotshell will probably give you the best patterning results in number 1 buck. This load may not be a good choice for those who are recoil sensitive.
Third choice is any standard or reduced recoil 2 ¾-inch #00 lead buckshot load from Winchester, Remington or Federal.
If you choose a reduced recoil load or any load containing hardened Magnum #00 buckshot you increase the risk of over-penetration because these innovations assist in maintaining pellet shape integrity. Round pellets have better sectional density for deeper penetration than deformed pellets.
Fourth choice is any 2 ¾-inch Magnum shotshell that is loaded with hardened, plated and buffered #4 buckshot. The Magnum cartridge has the lowest velocity, and the lower velocity will help to minimize pellet deformation on impact. The hardened buckshot and buffering granules also help to minimize pellet deformation too. These three innovations help to maximize pellet penetration. Number 4 hardened buckshot is a marginal performer. Some of the hardened buckshot will penetrate at least 12 inches deep and some will not.
Shotgun Slugs, Flechettes and Exotic Ammunition for Home Defense?
Unless you live on acreage and anticipate engaging bad guys at distances beyond 25 yards, shotgun slugs are not a good choice for home defense, because of their enormous capability to over-penetrate a human body and common building materials.
Some shotgun cartridges are loaded with flechettes. These are small, steel, pointed dart-like projectiles with aft stabilization fins, and are commonly referred to as "nails with tails." The low cross sectional area of a single flechette, combined with the small amount of flechettes that can be loaded into a shotshell, makes them an inferior choice for home defense when compared to buckshot.
Also, according to Second Chance Body Armor Company, flechettes are not effective against soft body armor, if this is a particular mission requirement for your ammunition. Steel shot also is ineffective against soft body armor.
There are other various exotic shotshells that are best classified as gimmicks. These include rubber buckshot, bean bags, steel washers, rock salt, "Dragon's Breath," bird bombs, ceramic slugs, "bolo" projectiles and so on. The efficacy of these loads is questionable at best, and we advise you to avoid them altogether for this simple reason.
Summary
With the right load, a shotgun can be very effective in quickly stopping the deadly violence being perpetrated by a criminal who's invaded your home.
If you're worried that a missed shot might penetrate through a wall and harm others, load your shotgun so that the first one or two cartridges to be fired is number 6 or smaller birdshot, followed by standard lead #1 buckshot (12 gauge) or #3 buckshot (20 gauge). If your first shot misses, the birdshot is less likely to endanger innocent lives outside the room. If your first shot fails to stop the attacker, you can immediately follow-up with more potent ammunition.
With birdshot you are wise to keep in mind that your gunfire has the potential to NOT PRODUCE an effective wound. Do not expect birdshot to have any decisive effect.
Number 1 buckshot has the potential to produce more effective wound trauma than either #00 or #000 buck, without the accompanying risk of over-penetration. The IWBA believes, with very good reason, that number 1 buckshot is the shotshell load of choice for quickly stopping deadly criminal violence.
End Notes
The term "Magnum" when applied to shotshells means "more shot." Magnum shotshells usually propel their pellets at a lower velocity than a standard shotshell.
Shotgun barrel length does not affect our shotshell recommendions.
References
Cotey, Gus J.: "Number 1 Buckshot, the Number 1 Choice." Wound Ballistics Review, 2(4), 10-18, 1996.
MacPherson, Duncan: "Technical Comment on Buckshot Loads." Wound Ballistics Review, 2(4), 19-21, 1996.
MacPherson, Duncan: Bullet Penetration, Ballistic Publications, El Segundo, California, 1994.
DiMaio, Vincent J.M.: Gunshot Wounds, Elsevier Science Publishing Co., Inc., New York, New York, 1985, pp. 163-208.