Bullet Wound Anatomy

Anatomy of a Bullet Wound

One of the tools used to compare the effects of ammunition is the "wound profile." Wound profiles are simply dimensioned photographs or carefully prepared scale drawings of test firings in calibrated ballistic gelatin. The wound profiles below are some typical examples of what a bullet does on impact.

Properly prepared and calibrated ballistic gelatin gives performance and penetration results within about 2 percent of of results obtained in actual tissue. "Properly prepared" means that the gelatin is a 10 percent mixture of ballistic gelatin (Kind and Knox Type 250) prepared water heated to no more than104° F (40° C) and then stored and shot at a stabilized 39° F (4° C).

.45 Silvertip 185gr wound (77k gif)

This particular profile is that of an early .45ACP 185gr. Silvertip Winchester @ 940 f/s. This is a classic non-fragmenting expanding bullet wound profile. The narrow portion at the start of the permanent cavity is called the "neck" and its length is a function of the bullet's design. This particular load is a little short on penetration at 25cm (9.8") with an expansion of .85". As a comparison the Hornady +P 230gr XTP at 880 f/s gave 15.6" penetration and .72" expansion, the Hornady 200gr XTP at 850 f/s gave 18.5" and .54", the Winchester 230gr Black Talon at 858 f/s gave 13.5" and .73", and the Remington 185gr at 1020 f/s gave 10.5" and .83". Interestingly, Winchester must have got the word because a later lot of this ammunition gave 882 f/s and 11" of penetration and .74" expansion. For comparison the GI M1911 Ball ammo (230gr at 869 f/s) produced a penetration of 26".

.38+pSWCHP (12k jpg)

This particular profile is that of a ..38SPL +P 158gr. lead semi-wadcutter hollow point "FBI" load @ 880 f/s. This is another classic non-fragmenting expanding bullet wound profile. This particular load shows good penetration at 32cm (12.6") and good expansion at .59". Perhaps this is one reason that this loading has a good reputation on the street. The Winchester Black Talon 9mm 147gr JHP at 981 f/s produced an almost identical profile with penetration of 35cm (13.8") and and expansion of .61". In the .40 caliber ammo the profiles were very similar with the Hornaday 155gr XTP at 1090 giving 14.3" penetration and .57" expansion, the 180gr XTP at 970 f/s giving 14.5" and .67", and the Winchester 180gr Black Talon giving 13.4" and .68".

.357 125gr (15k jpg)

This profile is the Remington 125gr JSP .357 Magnum at 1390 f/s which has an excellent reputation on the street. Note the shape and size of the temporary and permanent cavities are very similar to the .38 Special round above and penetration is only about 1.5" greater. Expansion is .66", only .07" greater than the .38 round in spite of the vastly increased velocity. An excellent example of good bullet construction at work. The equivelent JHP round gives about 10 percent less penetration and a .70 expansion.

M855 5.56mm NATO wound (49k gif)

This profile is the M855 5.56mm NATO cartridge, with a 62gr steel core FMJ boat tailed bullet @ 3035 f/s. This is a classic fragmenting rifle bullet profile. Penetration is acceptable at 34cm (13.4"). Note the long narrow neck of about 9 cm (4") before the bullet tumbles and fragments. The original M193 55gr round produces a similar profile but it has a longer neck, and slightly smaller temporary and permanent cavities. Both of these bullets fracture at the cannelure at velocities above about 2700 f/s. Below that velocity the bullets simply tumble without producing the extensive permanent cavity much like the 7.62 mm M80 ball round.

7.62mm PS AK47 (17k jpg)

This is the wound profile of the 7.62x39 PS Steel Core AK-47 round at 2340 f/s. Great penetration but otherwise not very impressive, eh? The permanent cavity is flat in cross-section. I removed two sections so the image would fit on the page better. At around 60cm the bullet yawed downward and wound up base first as shown.

5.54mm PS AK74 (13k jpg)

This is the profile of the 5.45mm AK-74 round at 3066 f/s. The lack of fragmentation makes a smaller permanent wound cavity then that achieved by the M16. However, penetration in flesh is better because of no fragmentation. The permanent cavity is actually flat in cross-section due to the long narrow bullet's tumbling so it is not as effective as the M16 rounds.

M80 ball wound (18k jpg)

This profile is the M80 7.62mm NATO cartridge, a 149gr FMJ boat tailed bullet at 2730 f/s. This is a classic FMJ military bullet profile for modern non-fragmenting / non-expanding spitzer bullets. The bullet ends up base first at a penetration of 25.6". The permanent cavity is flat in cross-section. Note the long neck before the bullet starts to tumble, but in this case at only 2700 f/s and with its heavy jacket the bullet doesn't fragment. Interestingly, if this bullet is driven at 3000 f/s it fragments and behaves just like the M855 5.56mm bullet. Have you noticed the trend for FMJ spitzer flat base/spitzer BT bullets that do not fragment to end up base first?

.30-30 ST (19k jpg)

This profile is of the Winchester .30-30 170gr Silvertip at 2020 f/s. This is typical of medium velocity, expanding rifle bullets.

.30-06 150gr (24k jpg)

This profile is of the Winchester .30-06 150gr Softpoint at 2923 f/s. Note the larger permanent cavity than the .30-30 but almost identical penetration. Not something you want to get shot with.

#4 Buck (28k jpg)

This profile is of the wound created by a 12ga. 27 pellet #4 buck at 1350 f/s. Penetration depth of the deepest single pellet is only 10.6" with the majority between 6" and 10", which corresponds to the known performance of #4 buck--in other word erratic. #1, 00, or 000 buck are a much better choices giving penetrations of about 13", 14" and 15" respectively for standard lead buckshot. While I don't have any profiles available, reports I have received from testers indicate that the use of hardened and/or plated buckshot can provide about a 10-15 percent increase in penetration due to the lack of pellet deformation with the harder pellets.

gelatin block photo (27k jpg)

This is an actual photograph of the wound created by a 12 ga load of 1¼ ounces (about 169 pellets)of #4 shot (not buckshot) at 1200 f/s. The maximum penetration is about 11 inches but the majority of the shot is located between about 5½ and 7½ inches. The damage pattern is typical of shotgun wounds at field distances.

12ga Rifled Slug (14k jpg)

This profile is of the 12ga 1oz (437gr) rifled slug at 1513 f/s. That's about a 1" wound channel and 14" of penetration! Observed penetration for Foster type rifled slugs ranges from 14" to around 18" depending on brand and hardness. No wonder some professional hunters like the 12ga slug as a bear stopper at close range. However, the soft lead slug doesn't fare too well on hard targets

Glasser safety Slug (18k jpg)

This profile is of the so-called "wonder bullet" the .357 Glasser Safety Slug, 80gr prefragmented bullet at 1785 f/s. This is typical performance of the ultra light weight, high velocity and prefragmented bullets in general . Note the very shallow penetration (4.7"). I'm not impressed, are you?

What to do, what to do...

While the energy dump school has been disproved there is still a minor battle going on between the temporary cavity and big hole schools, and perhaps the real answer lie somewhere between the two. There are many failures of both the high performance/high velocity temporary cavity loads (especially the lighter bullet weight loadings) and also the big bore/big hole loads. While general experience seems to favor the big hole loads, nothing is certain. A lot still depends on the condition of the target.

One famous case of small and fast failure (temporary cavity loads) was widely distributed in law enforcement training circles. A perp (Oops, excuse me--alleged perp.) received an incredible number of 9mm expanding bullets (somewhere around 36--all over his body including the chest and face) yet was not seriously inconvenienced for several minutes. Another similar case was the infamous FBI Dade County shoot out wherein one of the aggressively behaving antisocial misfits was hit solidly with a "high performance" 9mm 115gr JHP. Though the wound would have eventually proved fatal, it failed to penetrate deep enough. He was able to continue fighting and killed several agents with a rifle before being taken out of the fight with a more powerful and destructive load.

As to "big hole" failures, here in the People's Republic of NJ there was an incident awhile back that shook a lot of folks. A drugged up goblin was shot through the back door and seat of a van he was driving with a 12ga slug. He exited the van with an inch-and-a half hole blown clear through his chest. (Yes, Virginia, daylight was visible!) He ran about 25 yards firing his pistol at his pursuers until he collapsed. (And you thought you were well armed with your 9mm / .357 / 10mm / .45, eh?) Check the wound profiles above for the 12ga slug and compare it with a pistol bullet profile. Then ask yourself if you will ever feel well armed ever again. Under those circumstances a tactical nuke might have been needed to provide the needed incapacitation.

In the hunting area I'm sure that you have heard of accounts of Cape Buffalo receiving well placed hits of tremendous size and power (500 grains at 2000-2400 f/s) and who yet turned on their antagonist with malice afore thought and lethal intent even though the should have, by all rights, been dead on the spot.

Aways, keep this medical fact in mind:

Bullet hits to the torso cannot be counted upon to cause a person (or for that matter a game animal) to immediately cease his actions. Even a total loss of blood flow to the brain can still allow 10 seconds of purposeful action --more than enough time to empty a magazine into you or to stomp you to death.

As for me, even though there are no guarantees, I want to stack the deck in my favor as much as possible. I want to reliably cause the most damage possible with every shot. Since bullet expansion can't always be counted on due to intervening material and Hornady or Winchester don't offer tactical nuclear bullets, I don't like to count on a small bullet hopefully expanding to a bigger diameter. I like to stay with big at the start. Should I ever be lucky to go after dangerous big game I'll use all the gun I can handle. For personal defense I carry a .45 with 200-230 grain expanding bullets of proven design and penetration, but wouldn't feel too under gunned with a stout .40/10mm.

...and then there is always the Mozambique drill. But that's another topic.


Wound profiles courtesy Dr. Martin Fackler
Gelatin photograph courtesy of Letterman Army Institute of Research

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