Understanding First Round Pop in Suppressors
When using a suppressor, you might notice that the first shot is louder than the ones that follow. This phenomenon is known as "first round pop," and it occurs when residual oxygen inside the suppressor combusts on firing, creating a sharper-than-normal report. Most suppressors exhibit some degree of first-round pop, though its intensity can vary. In some cases, it’s barely noticeable to the human ear. In others, especially with rimfire suppressors, it can be quite pronounced. A variety of factors contribute to this effect, including suppressor design, ammunition, environmental conditions, and the host firearm.
Suppressor design plays the most significant role. In general, monocore baffle systems are more prone to first-round pop than traditional K-baffle or stacked designs. That said, even among monocore suppressors, performance can vary widely. Two rimfire suppressors with similar construction may behave very differently. Adding to the complexity, the host firearm has a major impact on the presence and severity of the first-round pop. For instance, a suppressor might produce noticeable pop on a pistol but run quietly on a rifle. Longer barrels burn more powder before the bullet exits the muzzle, which typically reduces the effect. This is why pistols and short-barreled rifles are more likely to exhibit first-round pop, even with a suppressor that runs quietly on a full-length rifle.
Environmental factors also come into play. High humidity can reduce or eliminate the first-round pop entirely. A suppressor that cracks loudly on a hot, dry afternoon might sound far more subdued on a humid morning. Moisture in the air can act as a natural coolant inside the suppressor, which leads to another option: running the suppressor “wet.”
Many rimfire and pistol suppressors can be used with a small amount of water or wire-pulling gel added to the baffles. This technique helps cool the expanding gases more quickly and significantly reduces the first-round pop. However, it also increases internal pressure, so it is essential to consult the manufacturer to ensure your suppressor is rated for wet use. The benefits of running wet are most noticeable in the first few shots, after which the effect gradually diminishes as the moisture evaporates or disperses.
Because the first-round pop is more noticeable on rimfire suppressors than centerfire models, it becomes an important consideration when choosing a rimfire can. Several models stand out for their minimal or virtually nonexistent first-round pop. Notable performers include the Dead Air Mask, SilencerCo Switchback, Thunder Beast 22 Take Down, and Rugged Oculus. With a basic understanding of what causes first-round pop, shooters can better evaluate whether it is a critical factor for their needs and choose a suppressor accordingly.
