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Every game has its recommended bullet energy transfer rating, usually pounds per square inch, which is recommended to kill that animal. That is, assuming that the projectile will completely stop in the animal thus transferring the total amount of kinetic energy to cause tissue and organ damage, it's recommended to use XXXXX Grain at XXXXX Feet per second or need at least XXXX pounds per square inch.

SO, I got to thinking, if humans had a rating or recommended bullet energy to take down what would it be? If I was going to size up the self defense ammo available and choose a weapon on the basis of what it actually takes to kill an assailant, what would I choose?

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Ok, I know how this sounds and I'm pretty sure I'll get some interesting opinions but somewhere in this thread I'm hoping to get some real data or a link. Here it goes...

Every game has its recommended bullet energy transfer rating, usually pounds per square inch, which is recommended to kill that animal. That is, assuming that the projectile will completely stop in the animal thus transferring the total amount of kinetic energy to cause tissue and organ damage, it's recommended to use XXXXX Grain at XXXXX Feet per second or need at least XXXX pounds per square inch.

SO, I got to thinking, if humans had a rating or recommended bullet energy to take down what would it be? If I was going to size up the self defense ammo available and choose a weapon on the basis of what it actually takes to kill an assailant, what would I choose?

Let me save someone some trouble here... I know that if I use a .50 BMG, regardless of how much overkill it may be, I'm pretty much guaranteed to kill an assailant. However, what I'm looking for is a way to "size" the right ammunition for the task and I don't care how "un-cool" it may be. If a .22lr would be enough (unlikely) that's fine with me.

And away we go...  

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Shot placement.


.

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This.

Also, regarding energy...the energy is only important while in the air.  You need to have enough energy available to ensure the minimum penetration of 12".  If we view humans as game, and not as someone to defend against, then overpenetration is not much of an issue.  In fact, the second exit wound would be preferred as another source of blood loss.

Terminal ballistics and the missile casualty become of importance to the military surgeon when the ordnance engineer asks for an opinion on the probable value of any given missile in producing a casualty. The ordnance engineer also requires a significant yardstick which may be mathematically applied in developing his designs of bullets, bombs, shells, grenades, or other missile casualty-producing agents.

Technical advancement has too often demonstrated the validity of the theoretical approach in design problems to permit the older rule-of-thumb or trial-and-error methods to be used in working up the instruments of modern warfare. Knowing the metal and detonating charge to be used in a given bomb, the ordnance engineer can readily calculate the number of fragments as well as their size and weight with probable distribution and velocities at any given distance from the point of burst. However, a criterion as to probable effectiveness is necessary if the data just cited are to be applied to practical design. During World War II, a criterion of a missile with weight and velocity sufficient to give it 58 ft.-lb. of kinetic energy was used in practice.

Though the adoption of the 58 ft.-lb. figure was arbitrary or empirical, it was much more practical than using the penetration of pine boards or other inanimate objects for the purpose. Selection of the figure was in a measure substantiated by the work of Gurney.9 This figure also was subsequently reasonably substantiated by the research of Harvey and his associates. It did supply a fully comparable yardstick on which to base theoretically relative efficiency.

9Gurney, R. W.: A New Casualty Criterion. Ballistic Research Laboratory Report No. 498, Aberdeen Proving Ground, Md., 31 Oct. 1944.

Initial velocity required for a 4/32-inch steel sphere weighing 2 grains was found to be 170 f.p.s. for penetration of human skin. Lead spheres having an 11/64-inch diameter, weighing approximately 7 grains with a velocity of 161 f.p.s., did not effect penetration. Even extremely large missiles will lose about 125 f.p.s. of their impact velocity in penetrating the surface of the skin. Area of presentation affects skin penetration to such degree that the loss in velocity is proportional to the reciprocal of the diameter of the spheres.

Skin was found to be more resistant than other tissues. The drag coefficient, a value dependent on the resistance encountered by a missile and independent of the missile, for human skin was 0.528 as compared to 0.297 for water. The coefficient for cat muscle was 0.448 and for 20 percent gelatin block, 0.350. Human skin had a drag coefficient more than 20 percent greater than cat muscle. While the drag coefficient was not determined, indications were that cat skin was slightly more resistant to penetration than human skin.

The skin resistance offered a logical explanation for the fact that shrapnel, formerly used as an antipersonnel agent, was commonly ineffective. It was usually employed at such ranges that remaining projectile velocity was low. The bursting charge propelling the shrapnel balls was commonly incapable of imparting sufficient velocity to effect skin penetration. Shrapnel balls also had a poor ballistic shape and were rapidly retarded in air flight.

18Grundfest, H., Korr, I. M., McMillen, J. H., and Butler, E. G.: Ballistics of the Penetration of Human Skin by Small Spheres. National Research Council, Division of Medical Sciences, Office of Research and Development, Missile Casualties Report No. 11, 6 July 1945.


An anomaly in skin penetration was the threshold velocity necessary to effect penetration, rather than a certain amount of energy. A 2-grain sphere required a velocity of 170 f.p.s. for penetration or a negligible amount of energy when measured in foot pounds. For a 150-grain bullet to penetrate skin, a velocity of approximately 125-150 f.p.s. was required corresponding to approximately 5 ft.-lb. of energy. The 2-grain sphere would have less than one-fiftieth this amount of energy.
Bone offered a situation similar to that found in skin. Here a minimal velocity of approximately 200 f.p.s. was necessary to effect penetration. Once penetration had been effected, any velocity remaining above the 200 f.p.s. would operate to effect deeper penetration in direct proportion to the square of the velocity and the sectional density of the missile. Penetration and damage to bone was effectively gaged by the amount of energy performing work, essentially proportional to the square of the velocity.

While specific experiments were conducted with beef bone, results are substantiated by other work with human and horse cadavers. Results were essentially the same.

In conjunction with these critical velocities necessary to effect penetration, some consideration should be given to the .45 caliber automatic pistol and its load. From time to time, complaint has been registered that this weapon is not as efficient under all conditions as could be desired in a self-defense weapon. A 234-grain full metal patch bullet is used, and it is launched with a muzzle velocity of 825 feet per second. Following is a tabulation of the kinetic energy available with this bullet at various velocities:

Considering the 125 f.p.s. required to effect skin penetration, it can be seen that the remaining velocity and energy are dropped down to at least 700 f.p.s. and 254 ft.-lb., respectively. The penetration of bone requires another 200 f.p.s. and dropping remaining velocity to 500 f.p.s. and energy to 130 ft.-lb. In addition to these losses, passage through tissue results in some retardation, so remaining velocity and energy will certainly be something less than the figures cited. Furthermore, impact seldom occurs at pointblank ranges, and

19Grundfest, H.: Penetration of Steel Spheres Into Bone. National Research Council, Division of Medical Sciences Office of Research and Development. Missiles Casualty Report No. 10, 20 July 1945.

the initial velocity is certain to be something less than 825 f.p.s. when the bullet hits the skin.

From an analysis of these facts and the requirements for penetration of skin and bone, it can be readily appreciated that the .45 caliber bullet is of little value as a wound-producing agent except in the softer tissues and at near ranges. The bullet often fails either to penetrate or to fracture bone and practically never shatters bone in the manner common to the rifle bullet or fragment. The Japanese and German sidearms with muzzle velocities of approximately 1,100 f.p.s. were much more effective as antipersonnel weapons than the .45 caliber weapon. While the same bullet with its characteristics was used in the submachinegun, multiple hits probably compensated for the weaknesses, so apparent in single shots.

Quoted:
Ok, I know how this sounds and I'm pretty sure I'll get some interesting opinions but somewhere in this thread I'm hoping to get some real data or a link. Here it goes...

Every game has its recommended bullet energy transfer rating, usually pounds per square inch, which is recommended to kill that animal. That is, assuming that the projectile will completely stop in the animal thus transferring the total amount of kinetic energy to cause tissue and organ damage, it's recommended to use XXXXX Grain at XXXXX Feet per second or need at least XXXX pounds per square inch.

SO, I got to thinking, if humans had a rating or recommended bullet energy to take down what would it be? If I was going to size up the self defense ammo available and choose a weapon on the basis of what it actually takes to kill an assailant, what would I choose?

Let me save someone some trouble here... I know that if I use a .50 BMG, regardless of how much overkill it may be, I'm pretty much guaranteed to kill an assailant. However, what I'm looking for is a way to "size" the right ammunition for the task and I don't care how "un-cool" it may be. If a .22lr would be enough (unlikely) that's fine with me.

And away we go...  

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6.8 SPC  1600 fpe.