When it comes to using a suppressor, more than just the suppressor impacts the volume of your gun fire. The ammunition you choose to fire also alters the sound and the decibels.

See, when you fire a bullet, three distinct sounds occur:

1. Muzzle blast: When a bullet leaves your gun’s muzzle, high temperature and high pressure gases closely follow it, escaping. These gases cause both a bright flash and a loud blast.
2. Sonic boom: Many bullets travel faster than the speed of sound (1,126 feet per second), causing a loud crack as the bullet forces its way through the air.
3. Mechanical noise: All firearms make mechanical noises when your fire them. This includes the movement of the slide or blot action.

The Right Ammunition for Your Suppressor

When you use a suppressor, you quiet the muzzle blast.  A suppressor essentially captures gases that escape your gun’s muzzle, forcing them into baffles where they cool and dissipate before their release. This works great to lower the volume of the muzzle blast, and in many cases, can allow shooters to forego hearing protection.

But a suppressor does nothing for the shockwave sound created from a sonic boom. That means if you shoot a bullet with a velocity greater than 1,126 f/s, the loud crack that accompanies firing a gun still occurs. Sometimes called the sonic signature, this sound lasts as long as the bullet travels faster than sound.

To rid yourself of the sonic boom, you must increase the bullet’s weight to lower the velocity of your ammunition. Because of the added weight, these bullets slow down and the velocity falls below the sound barrier threshold. Called subsonic ammunition, these cartridges only make a slight change when shooting an unmodified firearm, but from a gun with a suppressor, subsonic ammo can make all the difference.

With a quality suppressor and the right ammunition, you only hear a few decibels of mechanical noise, which you can’t eliminate.

And while a suppressor can’t really silence a firearm the way the movies do suppressed sniper rifles, with subsonic ammunition, it may not make it silent, but it sure makes it quiet.