(GunAuction.com) — Online retailer Cheaper Than Dirt recently posted an extended discussion entitled “The Myth of Handgun Stopping Power” in the company’s Shooter’s Log. Technical writer “CTD Mike” wrote, “When it comes to ammunition selection for personal defense, we need to separate real from hype before making a purchase. If you make a bad purchase on a vacuum or a home gym, you are likely to be a bit embarrassed. Making a bad purchase on defensive ammunition could have dire consequences. Let’s talk about some fundamentals so you’ll be able to make an informed decision.”

He continues:

Four terms need defining for us to understand how bullets work.

Penetration is the amount of tissue—bone, fat, and muscle—that a bullet passes through.

The permanent cavity is the amount of empty space—the hole—left in the body behind the bullet.

The temporary cavity is the momentary expansion of the permanent cavity stretching as the bullet’s kinetic energy is transferred to it.

Fragmentation is the separation of the bullet into smaller chunks, or pieces, which leave the permanent cavity and spin off in different directions.

Regardless of velocity, the bullet crushes the tissue in front of it as it penetrates or tunnels through that tissue. After the infamous “Miami Firefight”of 1986, the FBI set a minimum penetration requirement of 12 inches for their ammunition. This became the industry standard. All bullets penetrate and leave behind a measurable permanent cavity, even the .22 LR. All bullets also create a temporary cavity, although actually measuring it is nearly impossible. Fragmentation is dependent on two factors; bullet design and velocity. Impact velocities above 2,000 feet per second can cause fragmentation in full metal jacket bullets with thin jacketing, such as M193 5.56 NATO. Soft point or hollowpoint rounds may also fragment at the same velocities.

In rifle rounds, fragmentation accounts for a lot of the bullet’s ability to destroy tissue and stop bad guys in their tracks. Making slower pistol rounds fragment requires specialized bullet designs that fragment very easily. The problem with these rounds, such as the Glaser Safety Slug, is that they fragment immediately without penetrating. They are advertised as being safer to shoot indoors because they won’t penetrate walls and kill innocents on the other side. This is true! However, a round that can’t penetrate two layers of brittle sheetrock isn’t going to devastate a 250-pound man coming at you with a crowbar either. It will break up immediately upon hitting his skin, shower the first few inches of fat and muscle with little specks of lead, and fail to reach his vital organs. This is not what we want. At this time there is no magic pistol round that is safe when you miss, but “knows” when it hits a bad guy and decides that now is the time to penetrate and then fragment. Any round capable of penetrating tissue to FBI minimum standards is also capable of penetrating doors and walls. Fragmentation in pistol rounds falls into just two categories, won’t happen and fragments without penetrating.

The temporary wound channel is another factor we honestly can’t count on with pistols. Because it is known but not measurable, it has become the center of all sorts of marketing smoke and mirrors. For example, Federal Hydra-Shok ammunition was named for the concept of “hydraulic shock;” the idea that tissue not actually touched by the bullet could still be damaged by the “energy dump” or “kinetic energy transfer” of the bullet’s velocity to the surrounding tissue. The “energy dump” was the given reason why bad guys would be “knocked down” by the new hollow-point technology of rounds like the Hydra-Shok. Of course, there is no such thing as “knock-down power” with pistols, because no pistol knocks the shooter down when fired. Newton tells us that for each action there is an equal and opposite reaction. Therefore, the recoil your hand feels when you shoot a pistol is roughly equal to the amount of energy the bullet has as it leaves the muzzle, just compressed into a smaller, denser, much faster projectile. Getting shot by a handgun will not physically knock you down. I’ve been told it feels like being hit by a fastball, followed by a terrible stinging pain coming from your insides. Hydra-Shok is quality ammunition with a long track record in law enforcement and civilian use, but it physically cannot knock the bad guy over like we always see in the movies.

Tissue damage done through hydraulic shock is small even in many rifle calibers. In pistol calibers there is just not enough kinetic energy transferred to surrounding tissue to make any significant difference at all. That leaves us with penetration and permanent wound channel as the two ways pistol calibers consistently damage tissue. If penetration were all that mattered, we would all be carrying full metal jacket rounds like the military does. Of course, penetration is not everything. The military issues those FMJ rounds because under our interpretation of the Hague convention, hollowpoints are inhumane and contrary to the laws of war. The USA never signed the Hague convention but follows it strictly anyway, while other countries that did sign it have long since abandoned its outdated rules. I suppose the Hague Convention is why you’ll never see the USAF lobbing poison gas bombs from hot air balloons. For those of us who are not stuck in the 19th century, modern technology has provided the hollowpoint bullet.

A hollowpoint bullet fired from a handgun is designed to flatten out as it penetrates through soft tissue, staying in once piece but forming a “mushroom” shape with a wider diameter. This means less penetration than FMJ, but a bigger permanent wound channel. If penetration still meets the FBI’s required 12 inches, you get the best of both ways that a handgun bullet realistically damages tissue. What we want out of our handguns is 12 inches of penetration through soft tissue with the largest permanent wound channel possible. This maximizes our chances of directly damaging something vital.

This is the part where thousands of .45acp shooters smugly say, “That’s why I carry a .45, it puts ‘em down with just one shot.” I have seen this assertion many times on our Facebook page. Folks, you must hit something vital with any handgun bullet to quickly stop an assailant. A good friend of mine was in a shootout two years ago and was hit three times with .38 Special Speer Gold Dots before he even began to return fire. He scored two hits on the bad guy with .45acp Winchester SXT rounds (the ones that known as “Black Talons” back in the day) and the assailant ran off. The police followed a blood trail for eight hours before finding the bad guy hiding in a closet. Both men survived. My friend was the star witness at the bad guy’s trial, where they sentenced the bad guy to life in prison plus 30 years. The .45acp did save the day, but it did not physically stop the assailant. He simply ran away because someone was fighting back and his revolver was empty.

That is a lot of good information.  I have carried many different handguns in different calibers over the past few years.  Never really thought about all the technical points to what ammo I was carrying at the time.  I also have never planned to use a gun other then when hunting since my military days ended.  When reloading or working on ammo for specific uses, this type of information and other technical information (i.e. case type, primer, propellent, bullet specs., velocities, drop, range)  comes into play, but mainly with rifles.  Amazingly I never carried over the information to my handguns.  Well maybe my backups need more time and care then I have been giving them!  Then again, my carry does have hollow points in the mag. when not at the range.  And I just recently learned about dram equivalent in shotgun shells.  All this time reloading and buying shotgun shells and never paid any mind to it, so easy when velocities are on the box, but neat info that dram is.  At least my black powder cal.69 musket never was the wiser!