Ammunition

Terminal Ballistics

This is the third part of our study on ballistics. First, we looked at interior ballistics which is what happens when the shooter fires and the bullet is still in the gun. After that, we briefly examined exterior ballistics, which is what happens once the bullet leaves the muzzle of the gun and the forces that act on it as it travels to the target. Now we will look at terminal ballistics. This is what happens once the bullet arrives at the intended destination.

Bullet Impacting Brass Rod
Terminal ballistics is the study of what a bullet does when it impacts a target that is either animate or inanimate. Terminal does not specifically mean killing something. While death may be a result, our study is not limited to just that outcome. When correctly defined, terminal means the end of a process or series of events. What does the bullet do when it strikes its target? Does the bullet expand or remain pristine? Does the bullet penetrate or just impact the surface? Does the bullet do too much damage to the target? These are all part of the study of terminal ballistics, which is simply the target’s affect attained by the bullet.

Expanded bullet
The study of terminal ballistics has varied over the years. At one time, it was politically incorrect to say that the goal was to determine the best bullet to kill an animate object. However, this is the very goal hunters are trying to achieve on their intended target. On human targets, the goal is to incapacitate as quickly as possible during a self-defense situation. The ability to get the person to cease whatever action it was that made you choose the ultimate course of reaction. Incapacitation needs to occur with as few shots as possible. In a military or law enforcement setting they are not limited to just a personal self-defense situation. However, the goal is still the same—to render the target incapable of further action as quickly as possible.

Handgun Bullet Energy Transfer
To achieve this goal we need a good transfer of energy from the bullet to the target. This is the core of terminal ballistics. This energy transfers when the bullet is in contact with or passing through the target. Once the bullet exits or stops in the body cavity, all transference of energy has ceased. The remaining energy is lost when the projectile exits after passing through the target.

In a civilian self-defense situation, remaining energy is not a good result if the bullet’s objective was to incapacitate the target with as few shots as possible. Moreover, in this situation we do not want a bullet with unspent energy hitting anything other than the chosen target. Military objectives may be different as the goal is to incapacitate as many opposing troops as possible. A bullet with remaining energy is free to continue and strike additional targets. In terminal ballistics, this is the study of penetration.

When a bullet penetrates an animate target, such as a human or animal, it can display some strange reactions. These are dependent on where the bullet hits and what type of bullet is used. A fully jacketed bullet may have great penetration, but may cause very little energy transfer as it usually does not expand or fracture. A soft-nose or hollow-point bullet may have great expansion but may have trouble penetrating the target if it encounters obstructions. Incredibly, these obstructions do include clothing. When they hit denim clothing, handgun bullets have serious trouble expanding correctly. While this does not cause clothing to be in any way bulletproof, it does have a drastic effect on most defensive loads. Ideally, at least six to nine inches of penetration is the desired amount for self-defense rounds.

Bullet Cavity
As the bullet moves through the cavity, it will create both a permanent and temporary cavity due to a shock wave. The result of the temporary cavity can be very devastating since some internal organs are not flexible. If the projectile strikes bone, innumerable variables can occur. The bullet may pass through the bone, completely change its trajectory, break into fragments, or even explode which creates additional cavities.

Terminal ballistics is the study of kinetic energy transfer, penetration, and incapacitation of the target. Ammunition companies and re-loaders study this science to determine the best projectile to accomplish a given task. Ultimately, it does not come down to the firearm, shooters skills, or the years of practice. The action and reaction of the target cavity that the bullet strikes will determine the outcome of a defensive situation.

The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (12)

  1. Hi there,
    I was wondering if anyone can help me with some information – and even better, a photograph.
    I was shot with a 9mm bullet in an armed robbery in my home… (I live in South Africa) I was lying face down on the kitchen floor. The bullet went into my lower back, through my body, exited, then ricocheted off a tile and re-entered my stomach. There was clearly extensive damage to my body – but I survived, albeit a few months in ICU. I am an inspirational speaker and give talks on my survival. What I would like to include in my presentation is a visual of the projectile of a 9mm bullet – if there is an image of the projectile of a ricocheted bullet even better … that is what I think caused the most damage… the re-entry that is. Just by the way – I am a female, 5 foot 1 and 50kg… and my body survived the trauma I am happy to say…. The bullet (or whatever it is that it’s called when its spent) still resides in me. If anyone could help me …. even suggesting which of the pics on this site would be suitable for me to use to demonstrate to people what a little bullet can do, I would really appreciate it.

  2. The age old argument going around and around again.
    “I’ll only use this” or “I swear by that” – it gets tedious very fast.
    As Dave said above, shot placement is more important.
    Want proof?
    Would you rather be hit in the eye or nose area with a .22LR or take a 45 to the arm?
    Now get to the range with whatever caliber you want and practice hitting the target.

    If we just want to play the one-up game, then I say we “take off and nuke the entire site from orbit – only way to be sure” (Ripley – ‘Aliens’ 1986)

  3. Bullet placement is far more important than any gel or clay study.
    Is there any difference between the 1st generation Glock and the latest other than the grip and magazine?

    For stopping ability and long range accuracy
    Pistol << Rifle << Artillery

    The pistol is the only thing light and small enough for me for EDC. My ammo is essentially that every I can buy cheaply and for self defense Hydrashocks for the 9mm and 0.38 Spc HP +P to avoid over peneration and increase safety. I generally go for avoid a +P+ because it decreases my second shot speed and accuracy.

  4. As noted by others above, there is no such thing as ‘dumping energy’ kinetic or otherwise and the idea that this is what does damage to a target shows a horrible misunderstanding of what the ‘muzzle energy’ of a given round really means. In practice you’re much better comparing the relative momenta, but the entire bullet design matters to the terminal ballistic performance.

    I shoot 10 mm Auto, myself, from the Glock 20, though I’d like to try both the S&W and Colt platforms in the future. Fifteen rounds and a bullet that should always penetrate well and will probably expand nicely (if I use an HP design) seems to best fit the criteria for a self-defence pistol.

  5. So, this article provided a definition of terminal ballistics and provided some of the generally accepted performance measures. Ok, where is the rest of the article? Or was the intent of the author to pen a repetition of what we can get from wikipedia and receive a check from his employer? Please, if you are going to spend the time to write the article, post it on line and email the subscribers, take the time to at least make it valuable and interesting.

    For example, I test all my loads using raw pork shoulders (picnic style) at different ranges. This gives me a fairly good idea of the damage the projectile will produce once it penetrates flesh and hits bone. No ballistic gel, computer simulation or statistical model is going to be able to predict all possible variables better than real flesh and bone.

    Oh and here is some usable data. Out of the Glock 19, I have had the best results from the Remington Golden Saber JHP (http://www.cheaperthandirt.com/product/2-REMGS9MMC). Devastating damage to the target under 30 yards.

    For truly reliable damage, both in the open and thru medium cover (plywood walls and car doors), the 7.62x 39, out of any rifle its deadly.

  6. They myth of ‘energy transfer’ or any of it’s variants, ie., ‘kinetic dump’, are old ideas that were discredited years ago. The most accepted theories emphasize direct interaction between the projectile and target tissues through crushing and tearing. ‘Kinetic energy transfer’ and temporary stretch cavity have little to do with the actual wounding mechanism.

  7. For the last 30 years I’ve been a 45 guy. I would have nothing to do with anything else except a 357. the 380, 38, and 9mm were all on my “Anemic” list. I carried a 357 on duty for a few years then here come the 40 cal Glocks. The 40 was okay I guess but I hated the Glock… Well, now I’m older, retired and have major back issues. Last year I bought a Glock #19 for my wife. After many hours and dozens of guns. She grabbed a Glock 19. My last choice. But she felt it was a perfect fit. I fired it first to make sure it didn’t blow up or anything. Well, what do you know. The Glock 19 “Gen-4” was awesome. Way different than the first generation I so despised. I loved it and had to have one. I did some of my own tests and found with today’s new ammo, I could trust it with my life!!. Very light, very accurate, very reliable. All items you want in a carry gun. Add some “Hornady” Critical Defense ammo in 15 round mags?.. SWEET!!! In a SHTF situation I might go back to my trusty 100 yrd wheel gun. But for every day? the Glock.

  8. For the differance of 71 fps I’ll stick with my 40S&W w/180gr bullet. I still wish I had a 1911 but I don’t see that much differance to be concerned about when comparing the 45 to the 40. I never liked the 9.

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