READ THIS... Before posting nonsense about the efficiency of handgun calibers.

[TGO David]

While at first blush I was tempted to place this into the Ammunition and Reloading forum, it seems to me that this is in actuality the better place for it. Often the subject of "stopping power" in a handgun comes up on other forums and in physical conversations. To be blunt, the notion of "stopping power" from a service / self-defense handgun cartridge as it is envisioned by the general public is non-existent and therefore should not be the primary factor when choosing a handgun for self-defense.

It is my opinion and that of many others who know far more about the subjects than I do that you should chiefly choose a carry handgun based on how well you shoot it, how likely you are to carry it due to comfort / size / weight of the firearm, and how reliable the firearm will be. Without passing grades in these three areas, a handgun is in my opinion completely unsuitable for carry.

You will see from the chart below that when comparing well-designed defensive ammunition, there are minimal differences in penetration depths and in temporary cavity effects. This photo was provided by Doug Carr.

As you increase the diameter and mass of the bullet from 9mm / 357SIG, to .40SW, to .45ACP, more tissue will be crushed resulting in a larger permanent cavity. Also it should be noted that the larger bullets typical offer improved performance through "intermediate" barriers (clothing, vehicle and building construction, etc.). However it should also be noted that for some people, the benefits of the larger calibers is offset by the fact that a larger caliber typically begets a larger weapon frame which begets decreased ergonomics for the shooter depending on their physique.

The photo provided above makes it obvious that NONE of the common service pistol calibers generate temporary wound cavities of sufficient size that it would cause significant permanent tissue damage. Refer to “Handgun Wounding Factors and Effectiveness” produced by the FBI FTU, as this remains the single best discussion of the wound ballistic requirements of handguns used for self-defense -- it is available at: http://www.amazon.co...94498334&sr=8-1

So too is the notion of "expansion" or recovered diameter used to support the preference for larger caliber handguns. As seen in the photo above, the bullets recovered from ballistic gelatin show that modern defensive cartridges in the different calibers exhibit similar expansion diameters. Keeping in mind that it is not the size of the hole going in that is as important as the depth of penetration and the amount of bleeding caused within that affects the effectiveness of the bullet, one can see that choosing a handgun solely on the basis of caliber ignores far more important factors.

Primarily, you should choose the handgun for carry that:

• You are most likely to carry rather than leave at home
  
• You shoot the most accurately
  
• Offers the best reliability
  

Summary: Caliber used as the basis for choosing a defensive handgun is, within reason, bull$#!%. All modern service calibers provided comparable performance and all of them offer generally poor incapacitation ability when compared to rifle calibers. Therefore, choose the gun that you shoot best, that you're most likely to have with you at all times, and that won't fail to operate when you need it the most.

Source of much of the data contained within this thread: DocGKR on M4Carbine.net

[TGO David]

Continuing with those thoughts, let's discuss why penetration is more important than expansion or caliber size.

All too often we read comments on gun forums and hear comments in real-life discussions about the perils of "over penetration" in self-defense shootings and ultimately the conversation turns toward the notion that a mythical sweet-spot exists wherein a cartridge provides adequate penetration yet not too much. When you consider the dynamics of a self-defense encounter (the distance at which the shooting may take place, the way that the body of the individual receiving fire may be angled, intermediate barriers between them and the shooter, the anatomy of the individual being shot at, etc.) then it becomes obvious that it is quite literally impossible to load a cartridge that will provide just enough penetration for every single instance.

As illustrated in my preceding post, the temporary cavity effects and permanent tissue damaging effects of handgun cartridges make them poor performers when compared to the incapacitation qualities of rifle calibers. While a subject shot with a handgun caliber may indeed bleed out from a minor would given time, a self-defense shooting requires quicker incapacitation of the subject resulting in a more immediate elimination of the threat. Barring mortal injury to the central nervous system (CNS) via the bullets fired, the most effective means of dealing with the threat is to use a cartridge capable of penetrating deep enough into the subject so as to reach the large blood-bearing vessels and organs in the torso. Failing this, rapid physiological incapacity of the threat is unlikely.

In comparison, if a bullet completely penetrates and exits the subject, the bullet will have had enough penetration to reach the critical organs and vessels and will more likely have caused hemorrhaging sufficient to induce hypovolemic shock in the subject. Second to CNS trauma, this is the only reliable means of incapacitating the subject.

This bears out two points:

1. Shot placement is critical in any self-defense shooting, not only because of the liability attached to each bullet fired, but but also because failing to deliver shots accurately to the areas most likely to incapacitate the subject will result in that subject remaining a threat.

2. Penetration is king when choosing self-defense cartridges. If you have to choose between penetration and expansion, choose the former.