Terminal Ballistics – Part II
Welcome back to the second and final installment in the Terminal Ballistics series, which will also complete the Ballistics Series. In Terminal Ballistics I, we covered key terminology and highlighted the common goal of hunters, law enforcement, and home defenders… to incapacitate game animals or felonious assailants with as few shots as possible. We also covered the two methods that bring about incapacitation: a well aimed shot to the Central Nervous System (Medulla Oblongata or the upper spinal cord) and severe blood loss. In this article, we will cover projectile characteristics, best practices, and conclude the series.
Terminal Ballistics in Hunting and Personal Defense
With a wide variety of options in caliber, construction, and velocity, which combination is best? That is certainly a loaded question… pun fully intended. Short of providing overwhelming destructive force, which does not serve the hunter very well and is not typically an option for the home defender, the problem lies in having many options to address an even wider variety of possible conditions. Within these options lie a number of trade-offs. I’ll explain below.
As we’ve covered in the previous article, the most reliable method to take-down a game animal or end a felonious assault is to place an incapacitating shot into the central nervous system. In order to do this, a projectile of any caliber must possess sufficient velocity to penetrate the skin (animal or human), pass through layers of muscle and tendon, and destroy or at least interrupt the vital organs. Although it is often dismissed as an effective cartride, even a small .22 caliber long rifle projectile can accomplish this desired effect. However, as we’ve discussed at length, the central nervous system represents a disproportionately small area of the body in which this incapacitating shot can be taken. All other shots rely on severe blood loss, skeletal immobility, and shock.
All other things being equal (velocity, projectile construction, mass, etc.), penetration is essential to reach vital areas. This is where it can get confusing and the trade-offs take place. Since most projectiles are constructed with a combination of dense cores covered by softer metal jackets, small caliber projectiles will have a greater sectional density and thus require less velocity to penetrate. Robert Rinker equates this to comparing the force required to thrust both a small pin and a construction nail through remarkably pliable flesh. With greater sectional density and smaller diameter, the pin will require less force (momentum) to overcome the tensile resistance of the skin.
OK… so small calibers penetrate more easily. However, if it does not hit the small zone in which rapid incapacitation can occur, the small caliber projectile at high velocity can penetrate and pass through (often called over-penetration), leaving only a small permanent wound cavity which fosters only moderate blood loss. This can result in a lost game animal or an assailant who can continue the attack.
A projectile that expands on impact is beneficial since it creates a permanent wound cavity larger than the original caliber while maintaining the momentum of its original weight. However, rapid expansion hinders penetration.
So, both the hunter and home defender need to start with the terminal ballistic effect desired and work backward to develop a solution in terms of projectile construction, velocity, and firearm type. Hunters know thier game type and relative distances from which they will be taking the shot. External Ballistics Part III introduced velocity measurements and how to calculate residual velocity at different ranges. Home defenders know that the majority of pistol shots will be taken at roughly 20-25 feet. My recent article on Handgun Velocity demonstrated the effects of barrel length and temperature on velocities.
Armed with this knowledge in mind, here are some of the differentiating characteristics of projectile construction.
- Full Metal Jacket – A lead core is covered completely by a softer metal jacket, such as copper. Whether sharp tipped, round nosed, or flat, these penetrate and crush tissue along a permanent wound cavity which is roughly equal to the caliber. Small caliber high velocity full metal jacket projectiles can easily over-penetrate while large caliber low velocity full metal jacket projectiles will definitely crush tissue upon entry, but may not have sufficient penetration to produce the desired ballistic effect.
- Exposed Core or Semi-Jacketed – Instead of completely covering the lead core with a copper jacket, the jacket only covers the bearing surface of the projectile, leaving the lead core exposed from the shoulder through the meplat (tip). While these projectiles are typically lighter than full metal jackets, they are heavier than hollow points, ballistic tips, and frangible ammunition. With an exposed core tip, they maintain sufficient penetration while expanding only through high velocity or impact with semi-solid objects such as bone.
- Jacketed Hollow Point – A lead core is covered by a softer metal jacket which is folded over a blunt tipped cavity in the core. With sufficient velocity on impact, this cavity fills with tissue and fluid which causes the jacket and cavity walls to expand outward causing a permanent wound cavity larger than the original caliber while retaining its original weight. These projectiles can expand too quickly and prevent adequate penetration. Conversely, these projectiles may not expand at all due to insufficient velocity or the cavity becoming obstructed (typically by heavy clothing).
- Ballistic Tip – In order to ensure a sufficient ballistic coefficient and penetration, a jacketed hollow point projectile is “capped” with a polymer tip. This addition is designed to enhance accuracy and initial penetration, but break away upon impact and allow for traditional expansion within the body.
- Hybrid Projectiles – Lacking any other descriptive terminology, there are many projectiles that possess any combination of jacket, core, tip, and a filler. One example is the Glaeser Safety Slug, in which the traditional hollow point projectile is “filled” with bird-shot, and capped with a polymer ball. Because the lead core is minimized and both the shot and polymer ball are less dense than lead, these projectiles are lighter and their energy is rapidly consumed by the target in the form of rapid expansion and scattering of the shot. These are considered “safety” slugs since a missed shot will transfer its energy into walls, floors, ceilings, etc. which reduces the instances of collateral damage caused by projectiles continuing their travel and hitting an innocent bystander. The trade-off, however, is the possibility of insufficient penetration.
- Frangible Ammunition – Often described as lead-free, these projectiles do not contain a solid lead core. Instead, they are comprised of small metal particles bound together by an epoxy or similar bonding agent and encased in a very thin layer of copper or tin. Considerably lighter than any other projectiles of similar caliber, these projectiles are desinged to disintegrate on impact with anything more dense than themselves. Although these projectiles were initially designed for training (shooting steel or reactive targets at close range or indoors without creating a spall or ricochet hazard), some have touted these as acceptable home defense rounds. Due to their rapid disintegration, I do not believe they can provide sufficient penetration.
There are many other variations within and among these categories. Again, it is up to the hunter and home defender to determine the desired ballistic effect and choose the correct firearm/ammunition combination. In making these decisions, consider that extensive FBI testing concluded that adequate terminal ballistic effect takes place when expansion is combined with 12 inches of penetration.
Both hunters and forensics experts can tell you that no two shots are truly alike. Some will share similarities, but the distances, angles, positions and movements of both the target and the shooter, light conditions, and surrounding environment all differ to one degree or another. So, as a hunter or home defender, ample preparation can provide you with a comparative advantage to accomplish your goal of instantaneous or rapid incapacitation with as few shots fired as possible.
- Based on your anticipated conditions, choose a firearm and ammunition combination that will ensure expansion with 12 inches of penetration.
- Shot placement in the medulla oblongata or upper spinal cord with the correct projectile fired from the correct firearm is key. This requires some research and a lot of practice under as many realistic conditions as your training environment will allow.
- If a shot to the medulla oblongata or upper spinal cord is not possible, practice to attain center of mass shots to the upper torso, neck, and lower head.
- Practicing in a calm state of mind in the offhand or supported position on a well-lit range at a static target positioned perpendicular to the firing line is only one of hundreds of possible engagement conditions. Once baseline proficiency is gained, practice in low-light with strong-hand and weak-hand from behind a barricade engaging a target that is only partially visible and set at different angles.
- Understand that the engagement is not over until ALL threats have been incapacitated. Practice to search and assess in 360 degrees to determine that all immediate threats have been stopped.
- Take the time to think through your response options BEFORE any possible engagement. Routinely check your equipment (firearm, magazines, ammunition, flashlights, cell phones) and routinely practice the non-live fire aspects of the full spectrum of your response options. Don’t let your plan be defeated by the simple fact that the assailants did not follow the script you set for them.
- Think through your response options that will follow a live-fire engagement.
Thank you for your time and attention through the Ballistics Series. I’ve shared what has amounted to a lot of research combined with many years shooting pistols, rifles, and shotguns. With any luck, you’ve gleaned some useful information that you can put into practice or use as a foundation for further study. Wherever you are on your journey toward firearms proficiency, please realize that it is truly a journey and not a destination. All of the mentors at Aegis Academy are still continuing on our journey and we sincerely thank you for joining us.