Subsonic Ammunition: What It Is, Why It’s Useful
Ammunition that’s loaded so that the projectile travels under a certain velocity threshold is subsonic in that the bullet doesn’t break the sound barrier. As it happens, a heck of a lot of handgun ammunition is inherently subsonic, but that doesn’t necessarily mean much!
However, subsonic ammunition, like a hollow point, is a tool with an intended purpose. It has uses, many of which are practical beyond merely being quieter than a typical gunshot. Bear in mind that not all ammunition that is inherently subsonic is necessarily quiet, however.
This doesn’t mean you can or should shoot it without ear protection, of course; you should wear hearing protection at all times while shooting. In fact, just because a round is subsonic doesn’t mean it’s all that quieter. But with that said, let’s talk about what you can use it for and when subsonic ammunition is called for.
There’s Subsonic Ammunition And Then There’s Subsonic Ammunition
The word “subsonic” is much like other things in the gun community where there’s a technical meaning and then there’s a colloquial meaning, and you had better know the difference between them or else you might get yourself in trouble.
Technically, any ammunition that achieves less than supersonic velocity is in and of itself subsonic, which is 1,126 ft per second. That’s the speed of sound. Anything faster is supersonic, anything at or around that speed is transonic, and anything below that velocity is subsonic.
As it happens, a lot of handgun ammunition is in and of itself subsonic. Standard-pressure .45 ACP, with few exceptions, is almost exclusively subsonic. Heavy-for-caliber 9mm and .40 S&W loads, such as 147-grain 9mm or 180-gr .40 S&W, are subsonic, and so on.
Does that mean it’s quieter?
HECK NO. Standard-pressure .45 ACP and heavy-for-caliber 9mm ammunition still produces around 160 dB of noise when fired, which – if not wearing hearing protection – produces instant and irreversible hearing loss. Same story for rifle ammunition and shotgun ammunition.
However, there are also low-velocity subsonic loadings that produce less noise, due to the projectile being far slower than heavy-for-caliber loadings. Depending on the loading and the gun used in said ammunition, the noise level produced by the gunshot might be as low as 130 dB, or lower. However, again, it depends a heck of a lot on the loading and what gun it’s fired through.
For instance, SuperVel Hush Puppy 147-gr 9mm (made for use with suppressors) is loaded to 900 fps, which is around 50 to 100 fps slower than typical 147-gr ammunition. Hush Puppy 115-gr ammunition is loaded to 1000 fps, about 150 fps slower than typical 115-gr ammunition.
So when people say “subsonic”…it might not mean what you think it means. With that said, what purposes are there for low-velocity subsonic ammunition?
Subsonic Ammunition Is Ideal For Use With A Suppressor
If you’re going to run a can on your handgun or rifle, concurrent use of subsonic ammunition will get you the greatest noise reduction.
As we know, suppressors in and of themselves are basically a muffler that goes on the end of a gun. They don’t silence a gunshot; they just make them a little quieter, usually only providing a reduction of about 20 dB to 30 dB of noise.
When combined with a further 20 dB noise reduction with low velocity ammunition, the net result is a healthy reduction of noise level. A gunshot that normally produces 160 dB+ of noise could potentially be reduced to 120 dB of noise or even further, depending on all the circumstances involved.
That doesn’t mean you can shoot without ear pro; 120 dB is still not a safe noise level for extended periods. However, it is safer than 160dB+ without ear protection.
Thus, you can shoot plenty with a heck of a lot less punishment on your ears. If you’re going to be burning a heck of a lot of brass at the range, it’s fantastic.
Another use worth mentioning is small game hunting, as 22 subsonic loads can drop below 120 dB, with some even below 100 dB.
Subsonic Ammunition And Home Defense
Another potential use of subsonic ammunition is in home defense.
Imagine the following scenario:
Someone starts breaking into your home while you and your family are clearly there. The intruder is armed, and has made clear their intentions of coming in. You retrieve a pistol or rifle that you keep for home defense purposes and – when the target presents themselves – shoot them.
Besides the trauma of a home invasion, they also suffer hearing damage and a joyful spot of tinnitus. Every time their ears ring, they’re subconsciously reminded of the trauma, which means the implement that you used to save their lives is also worsening their post traumatic stress disorder.
This is why some vets can’t stand fireworks displays.
Granted, that isn’t an argument to not have a gun for defense. If you asked just about anyone if they’d take a bit of hearing loss over being murdered by a lunatic, no one in their right mind isn’t going to sign up for a bit of hearing damage.
Also, the odds that such an event will ever take place are pretty low. Odds that it would happen a second time? Preposterous…though it has happened to some people.
With that said, some people prefer to never have to worry about it and such keep a home defense gun with a suppressor or will employ low-velocity subsonic ammunition in their home defense guns just in case. Both handgun AND rifle rounds are available in this configuration; at home defense distances it will be effective if properly placed.
Granted, such ammunition will still be quite loud if unsuppressed, typically in the 130 dB to 140 dB range. It’ll hurt the ears, to be sure, but a lot less than a 160 dB+ gunshot.