AR15 Muzzle Brake/Flash Hider/Compensator Comparison, Part 2

Following up on the gargantuan first post of this comparison is a relatively short yet no less important portion. Especially to civilian shooters, the sound and blast of a muzzle device can be a huge turnoff. Yeah, that new brake keeps the muzzle on target, but if the noise rattles your friends every time you shoot the rifle, and other shooters on the firing line give you dirty looks and move away? Chagrin might give you second thoughts about your purchase.

For this portion of the test, a Brüel & Kjær 2209 Impulse Precision Sound Level Meter was used. Despite having been introduced in 1971 and looking quite like it could be an important quest item in Fallout 3, this is the device specified by the US Military and used by many silencer manufacturers to measure sound pressure level. The particular meter used for the test was provided by Rob Silvers of Advanced Armament Corp.

Since I forgot to take a better photo of the device, here's a cell phone pic.

Since I forgot to take a better photo of the device, here’s a cell phone pic.

As with the previous installment, scroll down to the charts if you’d just like to see the results.

Of course, all firearms are going to be loud. Even a silenced firearm with subsonic ammo makes noise. A rifle firing supersonic ammo without a silencer? Very, very loud. We are dealing with degrees of very loud here, but the difference between the loudest and quietest device (measured to the left of the muzzle) was approximately 8 decibels. Considering that a 10 decibel difference makes something sound twice as loud, these differences should not be considered entirely minor. If you would like to read some scientific papers regarding muzzle blast and gunshot acoustics, read this, this, or this.

But now, the charts.

First, using the military standard of 1 meter left of the muzzle and 1.6 meters above the ground, using Speer Gold Dot 64gr 5.56mm. These numbers represent the average of 10 shots.


After I had expended every round of .223 and 5.56 in my house, I used 5.45 to measure sound pressure levels at the shooter’s ear.


To be entirely sure of these results, I actually shot them all twice, on four separate days.

As you can see, there is a pretty clear line between muzzle devices intended to reduce recoil and those intended to reduce flash.