Brake. Hide. Compensate.
Short Story: Different muzzle devices do different things for different reasons. Review the benefits and drawbacks of each and figure out what will work for you and your application.
When it comes to threading something onto the end of your barrel, the options are seemingly limitless (paralyzing, even). Every AR builder deserves to understand the difference between a flash hider, a compensator, and a muzzle brake. And we might as well throw blast-forwarding devices, hybrid devices, and sound suppressors in the mix.
Let’s get down to dirt.
First things, first. All muzzle devices are designed for the same purpose: manage the gas escaping the barrel behind the bullet once the bullet exits the muzzle. From here, each type of muzzle device is designed to do something different with those gases. The device may do any of the following with the gas:
-
- Direct it laterally
- Direct it radially
- Direct it forward
- Direct it rearward
- Contain it and slow the release
The motivation for doing one or more of these things with the gas will inform the precise design of the device.
The table below summarizes the attributes and benefits of the different devices.
| Characteristic | No Device | Flash Hider | Compensator | Brake | BFD | Supressor |
|---|---|---|---|---|---|---|
| Muzzle Flash | Moderate | Low | Moderate | Moderate to High | High | Low |
| Concussion (Shooter) | Moderate | Moderate | Moderate | Moderate to High | Low | Low |
| Concussion (Side) | Moderate | Moderate | Moderate | High | Low to Moderate | Low |
| Concussion (Front) | Moderate | Moderate | Moderate | Moderate | High | Low |
| Recoil | High | High | Moderate to High | Low | High | High |
| Muzzle Rise | High | Moderate to High | Low | Moderate to High | High | High |
| Sound | High | High | High | High | High | Low |
Bare Muzzle (No Muzzle Device)
A bare muzzle may include a barrel with an unthreaded barrel or a threaded barrel with exposed threads or a thread protector.
Without a muzzle device on the end of the barrel, the exhaust of hot gas is very turbulent and uncontrolled. The gas will flow out of the bore in every direction and will swirl out of the barrel.
Flash Hider
Image Credit: Aero Precision
Image Credit: SureFire
A flash hider (also known as a flash guard, flash suppressor, flash eliminator, or flash cone) is the standard muzzle device found on military variants of the AR-15 (i.e. M16 and M4), as well as many other military firearms.
The purpose of a flash hider is, unsurprisingly, to reduce the visible signature of a firearm. It does so by 1) rapidly cooling the hot gas behind the bullet as it exits the muzzle, and 2) directing the gas away from the shooters line of sight.
Despite what some people believe, flash hiders DO NOT make a gun invisible and do not make a firearm more dangerous. The primary function of a flash hider is to reduce the flash from the perspective of the shooter, so that the flash does not temporarily blind the shooter (especially in low light conditions). While a flash hider can reduce the flash as seen from an observer, it will by no means make the flash imperceptible.
Flash hiders do not reduce recoil. Flash hiders do not necessarily compensate for muzzle rise. The A2 flash hider design can provide minimal compensation due to the presence of vents on the top, but not on the bottom (the lack of vents on the bottom is designed to reduce dust kicked up during fire).
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Compensator
Image Credit: Walker Defense Research
Image Credit: SLR Rifleworks
A compensator is designed to direct gas in a way that counters the movement of the muzzle that occurs when the firearm recoils against the shooter. This is awesome for shooters who need fast target re-acquisition and follow-up shots.
Some devices with a compensator feature allow the user to tune the flow of gas to compensate for the muzzle behavior in a very personal way. Probably the most tunable product that we have ever seen was the Ares Armor (then Blitzkreig Tactical) Effin’ A tunable compensator, which featured 24 threaded ports in 3 rows of 8 columns with threaded plugs to fine tune the exhaust pattern of gas.
Image Credit: Ares Armor
There are some others, like the Precision Armament HYPERTAP, that require progressive drilling of top ports to fine tune the counteracting exhaust.
Most compensators are not designed to hide the muzzle flash. There are some hybrid devices that compensate and reduce muzzle flash (e.g. the SureFire Warcomp).
Compensators do not reduce recoil. However, many compensators are hybrid brake-compensators (e.g. the Precision Armament HYPERTAP), which are very effective at both reducing recoil and muzzle rise.
Compensators are generally meant for shooting off hand. They use the force of the gas in a way that counteracts the recoil-induced muzzle rise, thereby reducing the time needed to reacquire sight picture and initiate follow-up shots.
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Muzzle Brake
Image Credit: Precision Armament
Image Credit: VG6
A muzzle brake (as in “pump the brakes”, not “take a break”) is designed to direct gas laterally, but at a slight rearward angle. By expelling gas toward the rear, the gas forces the muzzle forward. This can counter the rearward impulse and reduce the perceived recoil, especially in larger caliber firearms.
If you haven’t checked out our Mass and Gas topic or our Gas System Deep Dive series, we recommend that you do. Muzzle Brakes are a great complement to a finely tuned gas and reciprocating mass system.
While a muzzle brake can reduce the visible flash from the perspective of the shooter, it is not intended to hide the muzzle flash.
Muzzle brakes generally do not compensate for muzzle rise. However, the reduction in rearward recoil does tend to reduce muzzle rise indirectly.
Muzzle brakes are best used for guns that you will be shooting prone and supported, especially since they tend to add a good amount of weight to the end of the gun. Their benefits are greater for larger (and harder kicking) calibers, though they can be used on any gun. Muzzle brakes are NOT great for making friends at the range. The concussion is directed (and sometimes amplified) to the sides. If you’ve ever stood next to someone shooting a braked .300 Win Mag, you’ve probably dropped that magical “F” word and shifted to a position farther away. It is NOT pleasant to be to the sides of a braked rifle.
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AR Pistol
AR Carbine
AR Rifle
Blast-Forwarding Device
Image Credit: Noveske
Image Credit: Troy Industries
A blast-forwarding device (BFD), or linear compensator, does exactly what you think: it is a conical device that directs the blast and concussion forward, away from the shooter (and anyone standing next to the shooter). These are great for AR pistols and SBRs, which have significantly greater concussive blasts than their longer-barreled equivalents due to the higher pressures and higher proportion of unburnt powder at the muzzle. They are also great when shooting in enclosed spaces (i.e. in a building or CQB).
BFDs do a good job of directing blast away from the shooter, so it can have some flash hiding benefit to the shooter. They DO NOT reduce the blast from the perspective of observers. One excellent BFD is the Noveske KX3. The nickname for this device is “flaming pig”. Can you guess why it carries that nickname around?
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Sound Suppressor
Image Credit: Silencer Central
We will cover suppressors in depth in another article. But, because its screwed onto the muzzle, we’ll touch on it briefly.
Sound suppressors, also known by the misnomer “silencers”, are devices that attach to the muzzle in order to contain and slow the release of gas.
By capturing and slowly (relatively) releasing the pressurized gas, the report of the firearm (the primary “boom”) can be significantly reduced. A suppressor DOES NOT, by any stretch of the imagination, silence a firearm. It can take a Glock 17 from 162db (which can cause immediate and permanent hearing loss) down to 126db, which is about as loud as a gas chainsaw running at full tilt 3 feet away. From a recreational perspective, a suppressor can make a shooting experience much safer and more comfortable for you and anyone around you. From a duty perspective, a suppressor can help to reduce the audible signature of a firearm, making it harder for an enemy to pinpoint the source location.
It should be noted that suppressors DO NOT address the sound of a supersonic bullet (the “crack”). The crack of the bullet breaking the sound barrier will be there (unless you use subsonic ammo) and everyone will hear it…
Because they contain the gases and release them slowly, sound suppressors do a good job of reducing muzzle flash.
Sound suppressors do not reduce recoil.
Hybrid Device
Image Credit: Precision Armament
Image Credit: Precision Armament
Some devices try to capitalize on the benefits of multiple categories of muzzle device. You will probably find lots of compensator/muzzle brake hybrids, which try to simultaneously reduce muzzle movement and reduce recoil.
It should be noted that, with a few exceptions, any device that tries to accomplish multiple effects (e.g. compensate and brake) will generally not be great at either effect. But there are exceptions, and among those are the devices designed by Precision Armament.
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Summary of Device Function
The function of each muzzle device option is best viewed collectively. As such, we have combined the gas flow diagrams, below.
Timing and Securing a Muzzle Device
In order for a muzzle device to direct the exhausting gases appropriately and consistently, the device must be timed/oriented properly and secured.
Some muzzle devices will require the use of either a crush washer or timing shims. Others have an integrated timing nut. Always consult the manufacturer’s instructions the appropriate method of installation.
Some muzzle devices require the use of extreme temperature grease, while others require the use of extreme temperature thread locker. Please read Lock and Lube for more information.
Crush Washer
Image Credit: Luth-AR
A crush washer is a cupped washer that deforms when compressed. Each face has a sharp metal surface that bites into the mating surfaces of the muzzle device and barrel. The deformation creates tension between the shoulder of the barrel threads and the rear surface of the device, and allows you to time the orientation of the device properly.
Devices that utilize a crush washer typically benefit from extreme temperature grease (DuPont Molykote G-Rapid Plus) to lubricate the threads during installation and to prevent seizing after installation.
Timing Shims
Image Credit: Precision Armament
Timing shims are thin discs of metal that are used as spacers between the shoulder of the barrel threads and the rear of the device. Unlike a crush washer, these do not deform significantly. You must use the right combination of shims to time the device for your barrel.
Devices that utilize timing shims generally benefit from extreme temperature thread locker (Rocksett Muzzle Adhesive) to lubricate the threads during installation and to prevent rotation after installation.
Lock Nut
Other devices may use an integral timing nut (similar to a jam nut on some free floating handguards). These devices are aligned and then the timing nut is tightened against the shoulder of the barrel threads.
Devices that utilize a timing nut benefit from the use of extreme temperature grease (DuPont Molykote G-Rapid Plus) to lubricate the threads during installation and to prevent seizing after installation.
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