{"id":3649,"date":"2021-02-18T08:56:02","date_gmt":"2021-02-18T08:56:02","guid":{"rendered":"https:\/\/www.ammoman.com\/blog\/?p=3649"},"modified":"2026-06-11T17:06:13","modified_gmt":"2026-06-11T17:06:13","slug":"subsonic-ammo-bang-without-the-sonic-boom","status":"publish","type":"post","link":"https:\/\/www.ammoman.com\/blog\/subsonic-ammo-bang-without-the-sonic-boom\/","title":{"rendered":"What is Subsonic Ammo: Bang Without The (Sonic) Boom"},"content":{"rendered":"

Putting Subsonic Ammo To The Test<\/span><\/h1>\n

We\u2019ve all heard the phrase \u201cfaster than a speeding bullet, but just how fast is a speeding bullet, anyways? Gun owners are very familiar with the sounds of a gunshot, but what sound does the bullet itself make as it heads downrange? You may own a suppressor, but what impact does the noise of the bullet in flight have on the noise of your shots? Let\u2019s look at how subsonic ammo can answer all those questions.\u00a0\u00a0<\/span><\/p>\n

First, a brief excursion into basic physics. The amount of force projected by any given bullet headed downrange is a function of the bullet\u2019s velocity and weight. Factory-made ammunition conforms to standards laid out by SAAMI, the <\/span>Sporting Arms and Ammunition Manufacturer\u2019s Institute<\/span><\/a>, which standardizes the specifications for any given type of ammo. This means that\u00a0 any given caliber can only produce so much force when it\u2019s fired. Want more oomph? Fire a more powerful cartridge, and take the hit in noise and recoil as well.\u00a0<\/span><\/p>\n

Because the power of any given round is more or less set by the SAAMI standard, ammo manufacturers use lighter or heavier bullets to vary the velocity of their ammunition (Force = Mass x Acceleration: It\u2019s not just a good idea, <\/span>it’s the law<\/span><\/a>!). The question then becomes, why would ammo manufacturers want to make slower rounds, such as subsonic ammo? Isn\u2019t fast always better?\u00a0<\/span><\/p>\n

Slow(er) And Steady Wins The Race<\/span><\/h3>\n

Not necessarily. Let\u2019s look at two reasons to use subsonic ammo in your firearm. The first is with a suppressor. A suppressor (or silencer, as they were originally <\/span>called<\/span><\/a>) is essentially a muffler that you put on the front of your gun. A suppressor reduces the noise from your gun by slowing down the escaping gases that are pushing the bullet out of the barrel. It also dampens the noise of the muzzle blast. However, it has no effect on any noise that the round itself makes as it heads downrange.<\/span><\/p>\n

The second reason to use subsonic ammo has to do with the motion of a bullet through the air. Objects travelling near or above the speed of sound create a shockwave of compressed air in front of them. There is a loud crack when they break through that shockwave that we call a sonic boom, and it makes a lot of noise. Bullets are stable and predictable, by and large, when they travel supersonic. Things get weird when they start to slow down because of wind resistance and pass back through the shockwave of the sound barrier. Moving through all that compressed air affects the flight of the bullet, and it starts to tumble, throwing the round off-course and away from the intended target.\u00a0<\/span><\/p>\n

Why Use Subsonic Ammo?<\/span><\/h2>\n

\"Testing<\/a><\/span><\/p>\n

In short, subsonic ammo is ideal for situations where you don\u2019t want your ammunition to make more noise than the sound of your gun firing. It\u2019s also useful in competitions such as Precision Rifle matches. It\u2019s quite common at a Precision Rimfire match to see targets beyond where a standard .22LR round slows down and is no longer subsonic and starts to veer off target. Subsonic ammo is very useful when shooting 22LR at longer ranges because it allows your bullet to remain ballistically stable at ranges where supersonic ammo would slow down and start to tumble. This is why you\u2019ll see that most, if not all, <\/span>22LR match ammo<\/span><\/a> is subsonic, and does not break the sound barrier when fired.\u00a0<\/span><\/p>\n

With that in mind, let\u2019s compare what subsonic ammo does compared to ammo that goes faster than the speed of sound. We\u2019ll shoot one type of supersonic ammo and one subsonic ammo in three different calibers. To reduce effects of the noise of the muzzle blast from the equation, each of the guns will use a suppressor. The guns we\u2019ll be shooting are a 300 Blackout pistol with a Sig Sauer suppressor, a 9mm Glock 19 with an Omega-K suppressor, and a Savage bolt-action 22 rifle with a CMMG suppressor.\u00a0<\/span><\/p>\n

Testing Subsonic Ammo<\/span><\/h3>\n

We\u2019ll be shooting and comparing five rounds each of the following ammo:\u00a0<\/span><\/p>\n

Prvi Partizan 125 grain 300BLK FMJ supersonic<\/a>
\n<\/span>Sellier & Bellot 200 grain 300BLK subsonic<\/a>
\n<\/span>Winchester 124 grain 9mm NATO FMJ supersonic<\/a>
\n<\/span>Prvi Partizan 158 grain 9mm FMJ subsonic<\/a>
\n<\/span>CCI Mini-Mag 40 grain 22LR supersonic<\/a>
\n<\/span>Wolf Match 40 grain 22LR subsonic<\/a>\u00a0<\/span><\/p>\n

We\u2019ll also measure the velocity of each round by using a digital chronograph placed 10 feet away from the muzzle of our guns. This will help us determine if each round did in fact travel at supersonic or subsonic speeds. We will use <\/span>a Larson-Davis LXT1-QPR<\/span><\/a> sound meter to measure the noise of each round as it passes through the target. The meter will be placed one yard beside a target that is 55 yards away from the shooting position, <\/span>similar to the setup that Larson-Davis recommends for firearms noise testing<\/span><\/a>.\u00a0<\/span><\/p>\n

The conditions on our test day were as follows:\u00a0<\/span><\/p>\n

Temperature: 61 degrees F
\n<\/span>Height: 30 feet above sea level (hey, it\u2019s Florida\u2026),
\n<\/span>Humidity: 72% (Did I happen to mention Florida?)<\/span><\/p>\n

In those conditions, the speed of sound turns out to be 1118.2 fps, or 762 mph. Let\u2019s see how each type of ammo did.\u00a0<\/span><\/p>\n

Subsonic Ammo Test Results<\/span><\/h3>\n

Prvi Partizan 300BLK Supersonic (5 shots)<\/strong><\/span><\/p>\n

\"Prvi<\/a><\/span>Average Velocity: 1979 fps \/ 1349.5 mph
\n<\/span>Minimum Velocity: 1912 fps \/ 1303 mph
\n<\/span>Maximum Velocity: 2020 fps \/ 1377 mph<\/span><\/p>\n

Average Peak db: 166 db
\n<\/span>Minimum Peak db: 166.7 db
\n<\/span>Maximum Peak db: 165.3 db<\/span><\/p>\n

Sellier & Bellot 300BLK Subsonic (5 shots)<\/strong><\/span>
\n\"A<\/a>
\n<\/strong><\/span><\/p>\n

Average Velocity: 898 fps \/ 612.3 mph
\nMinimum Velocity: 834 fps \/ 568.6 mph
\nMaximum Velocity: 986 fps \/ 672.3 mph<\/span><\/p>\n

Average Peak db: 139.8 db
\n<\/span>Minimum Peak db: 138 db
\n<\/span>Maximum Peak db: 142.8 db\u00a0<\/span><\/p>\n

Winchester 9mm Supersonic (5 shots)<\/strong><\/p>\n

\"Winchester<\/a><\/strong>Average Velocity: 1226 fps \/ 836 mph
\n<\/span>Minimum Velocity: 1204\u00a0 fps \/ 820.9 mph
\n<\/span>Maximum Velocity: 1248 fps \/ 850.9 mph<\/span><\/p>\n

Average Peak db: 154.8 db
\n<\/span>Minimum Peak db: 158.1 db
\n<\/span>Maximum Peak db: 153.6 db<\/span><\/p>\n

Prvi Partizan 9mm Subsonic (5 shots)\"Prvi<\/a><\/strong>Average Velocity: 944 fps \/ 643.9 mph
\n<\/span>Minimum Velocity: 922 fps \/ 628.6 mph
\n<\/span>Maximum Velocity: 958 fps \/ 653.2 mph<\/span><\/p>\n

Average Peak db: 143.8 db
\n<\/span>Minimum Peak db: 133.6 db
\n<\/span>Maximum Peak db: 149 db\u00a0<\/span><\/p>\n

CCI Mini-Mag 22LR Supersonic (5 Shots)\"22<\/a><\/strong>Average Velocity: 1226 fps \/ 836 mph
\n<\/span>Minimum Velocity: 1204\u00a0 fps \/ 820.9 mph
\n<\/span>Maximum Velocity: 1248 fps \/ 850.9 mph<\/span><\/p>\n

Average Peak db: 154.8 db
\n<\/span>Minimum Peak db: 158.1 db
\n<\/span>Maximum Peak db: 153.6 db<\/span><\/p>\n

Wolf Match 22LR Subsonic (5 shots)\"Wolf<\/a><\/strong>Average Velocity: 1067 fps \/ 727.7 mph
\n<\/span>Minimum Velocity: 1041 fps \/ 709.8 mph
\n<\/span>Maximum Velocity: 1041 fps \/ 741.8 mph<\/span><\/p>\n

Average Peak db: 144.4 db
\n<\/span>Minimum Peak db: 146.2 db
\n<\/span>Maximum Peak db: 141.1 db<\/span><\/p>\n

There Was Supposed To Be An Earth-Shattering Kaboom!<\/span><\/h3>\n

All of the subsonic ammo in our test averaged around 142 decibels, which is right in-line with testing done by Larson-Davis themselves. As a comparison, 142 db is about the same level as a firecracker<\/a> going off, and <\/span>that level of noise can harm your hearing<\/span><\/a>. However, it\u2019s important to note that the 142 db was recorded by a sound meter placed just one yard away from the path of each bullet.\u00a0<\/span>
\n