Carrying Concealed: What You Need to Know About Hypervelocity Handgun Ammo

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When it comes to rifle ammunition, the technology has been mostly stagnant for the past few decades, with a few incremental improvements to bullet performance. However, in the last few years the possibilities of cases capable of handling drastically higher pressures (SIG’s hybrid case for the .277 Fury, Federal’s peak alloy in the 7mm Backcountry) have redefined our knowledge of the possible.

On the handgun side, the sea change happened with the widespread adoption of the FBI Ammunition Testing Protocol, which grew out of the famed 1986 FBI Miami Gunfight. That tough protocol has made modern handgun ammunition perform much better, but now we might be on the cusp of “the next big thing” in handgun ammo, hypervelocity. We’ve had “+P” (extra pressure=extra velocity) ammunition for decades, but what I’m talking about is something relatively new, pistol ammunition that sends bullets heading downrange at carbine velocities—roughly 2,000 fps. And that’s where things get interesting. Read James Tarr review of clear gel blocks here.

Bullets can wound/incapacitate through three mechanisms—temporary wound cavity, permanent wound cavity, and hydrostatic shock. First, you have to remember that human flesh is elastic, and has a very high-water component. The temporary cavity happens when the bullet first impacts, and the flesh expands and stretches. Slow-motion footage of gel blocks shows sometimes fist-sized cavities occurring at the moment of impact, but then they instantly close up. Permanent cavities are the actual wound channel through flesh caused by the bullet cutting and tearing skin, muscle, organs, etc. With a handgun bullet, that permanent wound cavity is usually a narrow tunnel. Pistols are poor stoppers because they simply aren’t that powerful, and so there’s not much energy transfer when their bullets hit bad guys, but now we get to hydrostatic shock.

Rifle bullets are no bigger or heavier than pistol bullets, but they are far more effective due to their increased velocity. People are basically just collections of very watery organs. Think of the difference between poking a puddle with your finger, and slapping it as hard as you can with your palm, and you’ll start to understand hydrostatic shock, which is basically a pressure wave travelling through flesh. An energy transfer between the bullet and the bad guy that tends to disrupt the human central nervous system.

Interestingly, if that bullet just zips through the bad guy, there is less energy transfer. You get more of a pressure wave, more energy transfer, more hydrostatic shock, when that bullet is forced to decelerate in the bad guy. You only start seeing the effects of hydrostatic shock when bullets are 1,800–2,000 fps and faster. Which brings us to hypervelocity handgun ammunition.

Previously in this column, I’ve discussed the increased popularity of 5.7x28mm ammunition. This odd, bottlenecked cartridge sends bullets of 35–40 grains in weight downrange at 1,600–1,800 fps. In shootings, it has proven to be roughly as effective as standard hollowpoints, and likely that is due to at least some imparted hydrostatic shock, although it is at the very bottom end of the velocity range for that. KelTec just introduced the smallest 5.7 pistol yet, well-suited 
to CCW, but let’s talk traditional calibers. Currently, there are two players on the scene that I’m aware of, Liberty Ammunition’s Civil Defense rounds, and SIM-X, which is a new company.

Liberty’s Civil Defense 9mm+P load is a 50-grain JHP at an advertised 2,040 fps, and that’s not BS, I’ve found it will do 2,010 fps out of the four-inch barrel of a Glock 19. The bullet is homogenous copper, with a very large cavity and thin base. Upon impact, the hollowpoint tends to fragment into several petals which fly off in various directions. The thin base, which is shaped like a coin, continues on into the bad guy. The high velocity of these bullets causes a large (for a pistol) temporary cavity, and may—depending—transfer the kind of hydrostatic shock you normally only get with rifle ammunition.

SIM-X ammunition is new, and really leaning hard into the science of how and why hypervelocity handgun bullets work. They’ve done a lot of testing under high-speed cameras, and have captured what they think are cavitation bubbles in gel blocks caused by the pressure wave of the impacting bullets. Their DefenseCore 9mm features a 45-grain JHP bullet at an advertised 2,250 fps.

Modern manufacturing technologies are allowing companies to do things that simply weren’t possible just a few years ago, and that includes projectiles. If you look closely at the 45-grain SIM-X bullet in the photos, you’ll see that it’s longer than the 50-grain Liberty Ammo bullet. That’s because the Liberty Ammo bullet is a traditional copper-solid JHP, just very short and with a huge cavity. The SIM-X bullet is basically a homogenous copper shell with a polymer filling. There is a cavity at the front to form a traditional hollow point, but upon impact the hollow point doesn’t expand; instead, the base of the SIM-X bullet collapses forward and the sides of the bullet blow out. It hasn’t been used in any defensive shooting yet that I’m aware of, but on hunts it has worked very well.

There is no such thing as a free lunch—these very light, very fast bullets don’t penetrate gel blocks/bad guys as deeply, as they arguably don’t need to. However, they also don’t penetrate barriers (drywall, auto glass, etc.) well, if at all. This drastically reduces the chances of overpenetration, but if you’re hoping to shoot through the kind of intermediate barriers traditional bullets have little problem with, these bullets might not be for you.

We are just starting to explore hypervelocity handgun rounds, and it makes me wonder…I wonder if the high-pressure cases we’re currently seeing on the rifle side are going to make their way over to the pistol side, providing even more velocity to these light-for-caliber loads. 

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