What is a Subsonic Round?

A subsonic ammunition round is a type of cartridge specifically designed to have a projectile velocity below the speed of sound, which is approximately 1,125 feet per second (fps) or 343 meters per second (m/s) at sea level under standard atmospheric conditions. By keeping the bullet velocity below the speed of sound, these rounds significantly reduce the noise produced during shooting, as they eliminate the sonic boom or “crack” associated with supersonic projectiles.

Subsonic ammunition is often used in combination with suppressed firearms, also known as silencers or suppressors, to further minimize the noise generated by shooting. This combination can be particularly useful in tactical scenarios, such as military special operations or law enforcement, where stealth and discretion are essential. Subsonic rounds are also popular among recreational shooters and hunters who want to reduce the noise levels at shooting ranges or while hunting to avoid disturbing nearby residents or wildlife.

To achieve subsonic velocities, these rounds typically use heavier bullets and reduced propellant charges compared to standard ammunition. The heavier projectile helps to maintain adequate energy and terminal performance at lower velocities. However, the reduced velocity can also result in a more pronounced bullet drop and lower overall range, which may require shooters to make adjustments to their aiming techniques or ballistic calculations.

It is important to note that subsonic ammunition may not function reliably in all firearms, especially those with gas-operated systems that depend on the pressure generated by the cartridge. Some firearms may require modification or specific components to ensure reliable cycling with subsonic ammunition. Additionally, while subsonic rounds reduce the sonic boom, they do not eliminate the sound of the firearm’s action or the muzzle blast, which is why they are often used in conjunction with suppressors for optimal noise reduction.

KIR Ammo offers several types of subsonic rounds in multiple calibers. Check out all of our ammunition and favorite subsonic rounds.