Unraveling the Decibels of an AR-15
Being in the firearms industry, I often get asked about the noise level of various firearms, and the AR-15 is no exception. When firing, the sound produced by a firearm can be a significant concern for shooters and bystanders. In this “How loud is an AR-15 when firing?” blog post, I’ll delve into the factors that contribute to the noise of an AR-15, explore the decibel levels associated with different components and scenarios, and offer tips on how to mitigate the impact of firearm noise.
Table of contents
What Makes an AR-15 Loud
Muzzle Blast
The muzzle blast, or the high-pressure gases released from the muzzle when the gun is fired, is one of the primary contributors to the loud noise of an AR-15. As the bullet exits the barrel, it leaves behind rapidly expanding gases that create a powerful blast.
Supersonic Crack
If the ammunition used in an AR-15 is supersonic (traveling faster than the speed of sound), it produces an additional sound known as the supersonic crack. This sound is created when the bullet breaks the sound barrier and creates a shockwave as it moves through the air.
Mechanical Noise
The AR-15’s action cycling can also generate mechanical noise during firing. This noise comes from the moving parts, such as the bolt carrier group and buffer spring, as they reciprocate with each shot.
Decibel Levels of an AR-15: What to Expect
Average Decibel Levels
The noise level of an AR-15 can vary based on several factors, including the type of ammunition, barrel length, suppressors or muzzle devices, and the surrounding environment. On average, the noise level of an unsuppressed AR-15 firing standard ammunition is around 165 to 175 decibels (dB) at the muzzle.
Suppressed AR-15s
Using a suppressor on an AR-15 significantly reduces the noise level. While suppressors don’t make firearms “silent,” as often depicted in movies, they reduce the noise to more manageable levels. A suppressed AR-15 firing subsonic ammunition can produce noise levels around 130 to 140 dB, which is comparable to a loud rock concert.
Subsonic vs. Supersonic Ammunition
Subsonic ammunition, which travels at speeds below the sound barrier, produces lower noise levels compared to supersonic ammunition. By eliminating the supersonic crack, subsonic rounds reduce the overall noise signature of an AR-15.
Factors Affecting Noise Levels
Barrel Length
The barrel length of an AR-15 can substantially affect the sound it produces when fired. Generally, a longer barrel tends to result in a quieter gunshot than a shorter barrel. This is because a longer barrel provides more time for the expanding gas generated by the burning gunpowder to act on the bullet before it exits the muzzle.
When a cartridge is fired in an AR-15, the gunpowder ignites, creating a high-pressure gas that propels the bullet down the barrel. As the bullet travels through the barrel, it accelerates, and the gases behind it expand rapidly. With a longer barrel, the expanding gases have more time to push the bullet forward, which means the pressure drop at the muzzle is more gradual.
In contrast, a shorter barrel allows the gases to reach the muzzle more quickly, resulting in a more abrupt pressure drop. This rapid pressure drop can create a louder, sharper “muzzle blast” or gunshot sound.
Ammunition Type
The type of ammunition used in an AR-15 rifle can noticeably impact the sound it produces. Ammunition choices, such as the caliber and the bullet’s velocity, are crucial in determining the gunshot’s acoustic characteristics. Generally, higher caliber ammunition tends to produce louder and more powerful sounds due to the increased energy released upon firing. Additionally, supersonic rounds, which travel faster than the speed of sound, can generate a distinctive sonic crack as they break the sound barrier, adding to the overall noise. On the other hand, subsonic ammunition, designed to travel below the speed of sound, reduces the sonic crack. Furthermore, the design of the bullet, including its shape and material, can influence the sound produced when it interacts with the firearm’s barrel and the surrounding environment. Consequently, selecting the appropriate ammunition is important for performance and managing the acoustic signature of an AR-15 rifle. As with any firearm use, responsible shooting practices and proper hearing protection remain critical to safeguarding hearing health.
Environmental Conditions
The difference in decibels between shooting indoors and outdoors can be quite significant. When firing a gun indoors, the confined space tends to amplify the sound waves, resulting in a much louder and more intense noise. The hard surfaces in indoor environments, such as walls and floors, reflect the sound, causing reverberations that can further increase the noise level. The lack of open space also prevents sound dispersion, making the gunshot sound even more intense to the shooter and nearby individuals. In contrast, shooting outdoors allows the sound waves to disperse freely in the open air, reducing the overall decibel level. However, it’s essential to remember that firearms can still produce dangerously loud noise outdoors, and proper hearing protection should always be used to prevent hearing damage.
Mitigating Firearm Noise: Tips for Hearing Protection
Ear Protection
The noise generated by firing an AR-15 can be extremely loud, often exceeding 150 decibels (dB) or more. This is well above the level considered safe for prolonged exposure. Without any ear protection, this loud noise can cause immediate and long-term damage to the delicate structures of the inner ear, leading to hearing loss and other auditory issues.
By wearing proper ear protection, shooters can reduce sound exposure to a much safer level. Generally, well-fitted earmuffs can offer a noise reduction rating (NRR) of 20-30 dB, while foam earplugs can provide an NRR of 20-33 dB.
For instance, if an AR-15 firing produces a sound level of around 160 dB. Wearing earmuffs with an NRR of 30 dB could effectively reduce the noise reaching the ears to approximately 130 dB. While 130 dB is still loud, it’s much safer than the original sound level without risking immediate hearing damage.
Suppressor Use
A suppressor, commonly known as a silencer, can significantly reduce the sound produced by an AR-15. The main principle behind a suppressor’s function is to slow down and cool the high-pressure gas that propels the bullet. This reduces the intensity of the muzzle blast and sound signature. As the bullet travels down the barrel, the suppressor’s internal chambers and baffles allow the gas to expand and dissipate gradually. This will lower the pressure before the gas exits the muzzle. This controlled expansion and dissipation of gas result in a quieter discharge than shooting without a suppressor.
On average, a well-designed suppressor can reduce the noise level of an AR-15 by approximately 20-35 decibels (dB). For instance, if the unsuppressed gunshot produces around 160 dB of noise, the suppressor can bring it down to approximately 125-140 dB. While this is still loud and hearing protection is still recommended, the noise reduction can make shooting more comfortable and decrease the risk of hearing damage. Additionally, suppressors can also reduce the audible range of the gunshot. It’s essential to note that the exact amount of noise reduction can vary based on factors such as the suppressor’s design, ammunition used, and shooting conditions.
Distance and Shooting Position
Position yourself safely from other shooters, especially when shooting in a group. Being too close to another shooter’s muzzle blast can increase the overall noise exposure.
How loud is an AR-15 when firing? Conclusion
We all must understand the significance of responsible shooting practices and prioritizing hearing safety. When firing, the noise of an AR-15 can be significant, especially when using standard ammunition and shooting without hearing protection. However, with proper knowledge and precautionary measures, you can enjoy the shooting experience while minimizing the impact on your hearing.
How loud is an AR-15 when firing? FAQs
exposure to high levels of firearm noise without hearing protection can lead to hearing damage or loss over time. Prolonged exposure to noise levels above 85 dB can cause permanent hearing damage.
Yes, using earmuffs and earplugs together provides additional hearing protection. It can be particularly beneficial when shooting powerful firearms like the AR-15.
No, shooting an AR-15 indoors without hearing protection is not safe. The confined space can amplify the noise, increasing the risk of hearing damage. Always wear appropriate hearing protection when shooting indoors or outdoors.
No, suppressors do not make firearms completely silent. While they significantly reduce noise levels, an AR-15 with a suppressor will still produce some sound when fired.
