Ok...Here's some info that I have collected. I don't know how accurate any of the info is as I am not at any of the testing sites. You read and you decide. I hunted as a youth and I still like to shoot stuff on an ongoing basis, so I know a bit about what shotgun shells do. I'll give you some snips with the URL. Please go to the pages and read what they have to say, then get some shot shells and go shoot some stuff. You'll figure it out. Shooting is experiential...
Shotgun Pellet Wound Ballistics
A shotgun pellet produces wound trauma by crushing the tissue it comes into direct contact with as it penetrates. In order to produce wound trauma that will be effective in quickly stopping an attacker, the pellets must penetrate his body deeply enough to be able to pass through a vital cardiovascular structure and cause rapid fatal hemorrhage to quickly deprive the brain of oxygenated blood needed to maintain consciousness.
Shotgun pellets are classified into two general categories: 1) birdshot, of which individual pellets are typically less than .20 caliber in diameter, and 2) buckshot, which varies in diameter from .24 caliber to .36 caliber...
...Birdshot, because of its small size, does not have the mass and sectional density to penetrate deeply enough to reliably reach and damage critical blood distribution organs. Although birdshot can destroy a great volume of tissue at close range, the permanent crush cavity is usually less than 6 inches deep, and this is not deep enough to reliably include the heart or great blood vessels of the abdomen. A gruesome, shallow wound in the torso does not guarantee a quick stop, especially if the bad guy is chemically intoxicated or psychotic. If the tissue crushed by the pellets does not include a vital cardiovascular structure there's no reason for it to be an effective wound...
...Many people load their shotguns with birdshot, usually #6 shot or smaller, to minimize interior wall penetration. Number 6 lead birdshot, when propelled at 1300 fps, has a maximum penetration depth potential of about 5 inches in standard ordnance gelatin. Not all of the pellets penetrate this deeply however; most of the shot will penetrate about 4 inches...
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...
http://www.firearmstactical.com/briefs10.htm
Shotgun Terminal Ballistics
..."A large slow projectile will crush a large amount of tissue, whereas a small fast missile with the same kinetic energy will stretch more tissue but crush less. If the tissue crushed includes the wall of a large blood vessel, far more damaging consequences are likely to result than if this vessel absorbs the same amount of energy in being stretched or temporarily displaced by cavitation."
The key in selecting effective wounding ammunition for deployment in a tactical shotgun is to balance the desire for multiple projectiles (higher first round hit probability) with each projectile's inherent capability to effectively wound. Hopefully our gelatin tests listed lower provide you with a bit more information to effectively evaluate the myriad of ammunition available as it relates to your own requirements...
http://www.tacticalworks.ca/ballistics_shotgun.html
Wound Profile Illustrations
..."The wound profile was developed at the Letterman Army Institute of Research in order to measure the amount, type, and location of tissue disruption produced by a given projectile, and to present the data in a standardized, easy to understand picture.
"The entire missile path is captured in one or more 25 x 25 x 50 cm blocks of 10% ordnance gelatin at 4°C. The penetration depth, projectile deformation and fragmentation pattern, yaw, and temporary cavity of the missile in living anesthetized swine tissue are reproduced by this gelatin. Measurements are taken from cut sections of the blocks after mapping of the fragmentation pattern with biplaner x-rays. These data are then reproduced on a life sized wound profile which includes a scale to facilitate measurement of tissue disruption dimensions, a drawing of the loaded cartridge case before firing, the bullet weight and morphology before and after firing (and calculated percent of fragmentation), and the striking velocity...
http://www.firearmstactical.com/wound.htm
Finally two sites about shooting stuff...
http://www.theboxotruth.com/
http://www.ar15.com/forums/topic.html?b=1&f=5&t=461635&page=1
I load Number 1 Buck, and I'm stickin to it...so that's my vote.
