Throttle Me! Why Speed Matters in Terminal Ballistics
Over the course of a year, we talk to a TON of shooters. One question we commonly get asked is, “What is the weight of the projectile?” Oftentimes we’re talking about 9mm, and of course there are plenty of bullet options for that cartridge. We tend to favor high quality, purpose driven, lighter projectiles. Upon hearing our answers surprisingly the “expert” will shake their head, scoff at the answer, and say something along the lines of, “Nah, too light for me”, or “124 grain is the BEST”, or “Such a wimpy round.” It is one thing if it’s a matter of personal preference and the recoil signature is something your used to, but we often follow up with the question, “Why?”. While we have heard a hell of a lot of answers to this questions, many times the answer amounts to the same general premise, “Oh it packs more of a punch.” or “It just hits harder!” Or something along those lines. Now I’m assuming when the person says something along those lines, they are talking about kinetic energy.
In the field of ballistics, the term “terminal ballistics” loosely refers to how a projectile behaves, and the resultant outcomes of imparting kinetic energy to a target upon impact. Ballistic testing and game based necropsy show time and again that terminal ballistic performance varies within the same caliber family. Variables such as projectile construction, weight, design, velocity on impact, sectional density, and projectile expansion rates are the most commonly cited contributors to this variability. From a functional perspective, while all play a role, one is a stand out when talking matters pertaining to kinetic energy.
What many of us have forgotten from high school physics is the equation for kinetic energy.
Kinetic energy (K) is directly proportional to the mass (m) of an object and to the square of its velocity (v). What that means is that if you double the mass of the object, you will double the kinetic energy. However, if you double the velocity of that same object, you effectively quadruple kinetic energy. Now we have a series of cartridges called the GTFO series (yes, that’s what it means) which our aim is to deliver the most kinetic energy possible for that cartridge. To do that, we find a well designed, lightweight m projectile, and charge it to the maximum possible velocity while safely operating within SAAMI pressures, and having a stable projectile. So before you reach for that thunder clapping-blunderbuss of epic proportions, and you really want to “pack the punch” remember, all things being equal…speed dominates.