Ask Foghorn: What’s The Difference Between a Muzzle Brake, a Compensator and a Flash Hider?

AAC Muzzle Brakes

I was sitting around with Kevin Brittingham and Reed Knight talking about gun stuff and one of the things they agreed was a mutual annoyance at how people don’t use the right word to describe the thing on the end of their muzzle. Heck, even some gun guys don’t really know the difference. So, at their request, I figured I would write a quick article trying to explain the difference between the three main muzzle devices in use today . . .

Flash Hider

When you buy an AR-15, or any modern rifle with a threaded barrel, the default muzzle device is typically a flash hider. It’s the standard issue muzzle device for the M16 and M4 rifles in the U.S. military, and since the current service rifle is the model for civilian firearms that’s what the gun companies use by default as well.

The idea behind a flash hider is pretty simple to understand. When a gun fires, especially a gun like the AR-15, most of the powder is burned inside the barrel and used to propel the projectile downrange. However, since the 5.56 NATO cartridge was designed to completely burn in a 20 inch barrel, there’s 4 missing inches that leads to some unburnt powder being left over after the projectile is long gone. That unburnt powder combusts as soon as it clears the end of the barrel, resulting in a large fireball that is very visible — especially on the battlefield. Even for civilian shooters, that fireball has a tendency to obscure the sights and make follow-up shots hard to make.

Muzzle Flash, c Nick Leghorn

A flash hider works by efficiently mixing the air and the unburnt powder at the end of the muzzle in such a way that there is no flash. To understand exactly how it does that requires a mixture of fluid dynamics and chemistry, a background that I lack. But you can see that it works by comparing a gun with a flash hider with one that only has a bare muzzle.

There are different kinds of flash hiders, and the most efficient are the three pronged variety. Whether manufactured by Knights Armament or Vortex or AAC, they all efficiently make that flash disappear. The birdcage flash hider that is used on most AR-15 rifles is also pretty efficient, but the real reason why it’s used is that it’s a combination flash hider and compensator.

Want flash suppression data on different devices? Check out Jeremy’s first flash hider roundup here and second one here.


A compensator or “comp” is a muzzle device designed to counter the vertical movement of the barrel. The body mechanics involved in firing a gun means that there’s a good bit of “muzzle flip” when the gun goes off, an effect where the recoil of the gun is translated into the muzzle climbing vertically. In order to counter that effect, a compensator vents some of the gasses from the barrel vertically. As we remember from physics every action has an equal but opposite reaction, so the gasses have the effect of forcing that muzzle back down on target.

The A2 birdcage flash hider (on the M16 / AR-15 rifle) has cuts on the top of the device that vent the gas and look like a bird cage, but the bottom of the device is solid. Not only does this keep the muzzle blast from kicking up much dust, but also provides a surface against which the gasses can push to force the muzzle back down.

Compensators and flash hiders are great, but they don’t do a damn thing to mitigate the felt recoil of the firearm. Something hard hitting like a .50 BMG rifle has a ton of recoil that, if not properly mitigated, can do some serious damage to your body. That’s where the brake comes into play.

Muzzle Brake

A brake is designed to take some of the kick out of the gun. As the bullet leaves the muzzle of the gun, the expanding gasses that follow quickly start escaping along the path of least resistance — which usually means slightly to the side and around the bullet. With a muzzle brake, those gasses first hit a solid metal wall before being vented out the sides. Once again the wonders of physics take over, and the pushing forward on that metal wall move the gun forward and counteract some of the rearward force of the gun.

While a brake can vent those gasses in any direction, most brakes vent the gasses straight to either side of the barrel and not vertically into the line of sight of the shooter. It also creates a pressure wave that moves horizontally along the firing line, often annoying those to the side of the shooter.

Another increasingly popular form of muzzle brake is the silencer. The baffles in the can that slow the gasses and turn that loud “BANG” into a more squishy noise also act like a massive muzzle brake and greatly reduce the recoil of the gun. That’s one of the reasons that a Neilsen device is required on a handgun silencer, a spring or piston that allows the barrel to recoil enough to kick the slide back and cycle the action as the silencer itself is being moved forward by the gasses.

Looking for data on which brakes brake the best? Check out Jeremy’s muzzle brake tests. First 5.56 test here, second here, third here. First .308 test here.

Combination Devices

Naturally, the ideal muzzle device combines one or more of the features of the devices above. That’s why combination devices, like the A2 flash hider or Precision Armament AFAB, are extremely popular. The most common muzzle device for competition shooters is the compensating muzzle brake, which reduces vertical muzzle climb and felt recoil without caring about the visibility of the firearm. As a result, some fantastic muzzle flashes can be seen in the chambers of the device as the gun goes off.

The ideal muzzle device, by any account, is a silencer. It reduces all of the above (well, after the first shot for muzzle flash) and does it extremely efficiently. That’s one of the reasons that muzzle devices come under heavy scrutiny in competition shooting since a bigger muzzle device can give a shooter an unfair advantage.

Personally, if I can’t have a silencer, I prefer a straight muzzle brake. Vertical climb is something I can handle with sufficient training, but any little bit of help I can get in the recoil department is always appreciated.

[Email your firearms-related questions to “Ask Foghorn” via [email protected]. Click here to browse previous posts]


  1. avatar natermer says:

    A flash suppressor hides the flash of your gun.

    A compensator blinds you temporarily if you have to shoot in the dark.

    A brake makes your gun noisy and unpleasant to shoot while irritating and making life unpleasant for the people that are to either side of you in a gun range.

  2. avatar John L. says:

    So … dumb question … What makes a really really good multifunction muzzle end device a silencer according to the rules?

    As in, what happens if you start out intending to design the ideal muzzle brake and wind up with something that also reduces the noise as a side-effect?

    Or perhaps to put it another way, is it intent or functionality that makes something a silencer? If the latter, what are the thresholds for when something requires a tax stamp etc?

    1. avatar JasonM says:

      18 U.S.C. § 921(a)(24):
      The terms “firearm silencer” and “firearm muffler” mean any device for silencing, muffling, or diminishing the report of a portable firearm, including any combination of parts, designed or redesigned, and intended for use in assembling or fabricating a firearm silencer or firearm muffler, and any part intended only for use in such assembly or fabrication.

      The first part refers to effect, not intent, so I’d say your accidental suppressor is restricted. It doesn’t list a minimum required noise reduction, so with any reduction, you’d be taking a risk.

  3. avatar David says:

    Also, the weight these devices (can) help control recoil & muzzle-flip. Sometimes just a longer barrel will accomplish recoil/muzzle-flip reduction as well as flash reduction . . . plus you get the added benefit of range and accuracy 🙂

    Also, here:

    “Compensators and muzzle brakes are great, but they don’t do a damn thing to mitigate the felt recoil of the firearm.”

    “That’s where the brake comes into play.”

    Maybe you meant flash hider?

    1. avatar JasonM says:

      plus you get the added benefit of range and accuracy

      That’s a common misconception, but barrel length does not always increase accuracy. A longer barrel will have more whip, reducing accuracy. But it will (usually) have a higher velocity, offsetting this decrease somewhat (but not entirely). Many precision rifle builders are producing rifles in the 20″ range. My precision .308 has a 20″ Krieger bull barrel, and it groups like a laser.

      1. avatar David says:

        Longer barrels general make the bullets fly faster but not always. Sometimes they can actually slow it down. I know that it is almost common knowledge that when handgun makers put out a slightly smaller version of a full size pistol that the smaller version will often have better accuracy than the full sized version – within a certain range.

        My point is – going w/ a longer barrel (instead of a flash hider or muzzle/comp) is sometimes a viable option that (can) have added benefits.

      2. avatar Skyler says:

        There’s a limit to everything. A longer barrel does not always increase velocity. If you make the barrel 100 yards long, I’m guessing the bullet will barely come out the other end.

      3. avatar Jonathan -- Houston says:

        I’d expect that with a chrome lined barrel, the longer the barrel, the greater the opportunity for imperfections in the chroming process to creep in, negatively impacting accuracy.

        That said, just about all of the factors discussed so far here either can be overcome by proper training, or will be overwhelmed by the effect of poor marksmanship to the point of being immaterial, anyway.

        1. avatar JasonM says:

          The whip effect is based on barrel harmonics. A longer barrel will flex back and forth more easily. High speed footage of barrels while firing shows that the barrel can be slightly off center when the bullet comes out of the end.

          For a run-and-gun carbine or hunting rifle, it’s not going to matter. But for a precision rifle, where 0.1″ makes the difference between first and last place, it matters.

      4. avatar Cyrano says:

        A longer barrel will typically do better at getting better powder burn and give you higher velocities. These higher velocities give you more time spent in supersonic flight thus no destabilization due to falling back below sonic speed before the target. A longer barrel also gives you a better sight radius for iron sight shooters. Barrel whip is almost imperceptible especially with the last device that was not mentioned in this article which is a barrel tuner. The use of a tuner can take out the “barrel whip” effect. There is more impact from a properly bedded barrel than one has to worry about barrel whip. You will get less performance at long ranges (600 to 1000 meters) or even short ranges (100 to 200 meters) if your barrel is 4-5 inches too short for the powder/bullet combo you are trying to project. If you are shooting for 1/4 MOA or less, you watch all the factors you can.

    2. avatar Stu says:

      I was going to bring up the same thing, David

  4. avatar dwb says:

    The Difference Between a Muzzle Brake, a Compensator and a Flash Hider is the difference between a legal firearm and really dangerous super nuclear tipped automatic child vaporizer with collapsible stock. And don’t ask me why, I just do what the rulers tell me to do.

    1. avatar ValleyForge77 says:


    2. avatar rlc2 says:

      You need to run for CA Legislature. You’d be a shoo-in.

      1. avatar Lynn says:

        That’s great but the California legislature needs shooing – out……

    1. avatar Tom in Oregon says:

      Doc, scroll up for the ‘you may also like’ posts. Click the first one. Best muzzle brakes/compensators…
      Mr. Leghorn is spot on with the examples.
      Trial and error are the best teachers for your specific gun/needs/caliber.
      Check out the competition shooters and their equipment. Especially folks who shoot ‘unlimited’ class.
      There is some neat stuff out there.
      I personally like the PRI MSTN QC brake for 5.56. It’s extremely effective. It’s 75-80 bucks most places.

  5. avatar ValleyForge77 says:

    I want a muzzleflashenbrakensator personally. Just can’t find the darn thang.

  6. avatar Dr Duh says:

    The BATF regulation is written in a practical manner, but I wonder if it would be susceptible to attack as ‘overly vague.’

    First, it refers to “report” but doesn’t say where that is measured.
    A muzzle brake reduces the report as measured in front of the gun, by redirecting the blast backward.
    While a Lavang directs blast down range, reducing the report at the shooter’s ear.

    Presumably, they mean total “report”. But if a SBR has a loud report because of more unburned powder exiting the muzzle then wouldn’t a 20″ barrel, which recaptures that kinetic energy as additional FPS then be a silencer?

    And if you want to be even more picayune, aren’t all muzzle brakes and compensators really just imperceptible silencers? Since they convert some of the kinetic energy of the blast, which would otherwise cause a sound wave, into mechanical energy to resist recoil and muzzle flip?

    An enterprising 2A lawyer might be able to wage a two pronged attack on this regulation, first by arguing that it is over vague, then making a workplace safety claim for hearing loss.

    I would consider it a win if you could get BATF to establish a minimum noise level for firearms, pegged to a safe level, say the 119db of an ambulance siren, then legalize any silencer that didn’t make your gun noticeably quieter.

    Even high quality hearing protection will only cut 30db off, that drops most loads to the 120s which can cause damage with repeated exposure.

    1. avatar Galtha58 says:

      @Dr. Duh, Don’t give the BATF any more ideas. They may come up with a rule that makes all guns illegal for being too loud, even with a silencer.

  7. avatar Taro Tsujimoto says:

    Now how about stressing that it’s a muzzle BRAKE, not a muzzle BREAK. That drives me nuts. Like using “breach” instead of “breech.”

  8. avatar Skyler says:

    Words words words. You call it what you want.

    The military has been calling it a flash suppressor for more than fifty years now. I don’t think “flash hider” has as good a pedigree. And now some people are calling silencers “suppressors,” further confusing the issue.

    I think it’s better to discuss the behavior than to pretend that certain words apply universally. And anyone claiming that their words are the final word lacks credibility.

  9. avatar Mark says:

    Let’s not forget those breachers!

  10. avatar Wagge says:

    “Compensators and muzzle brakes are great, but they don’t do a damn thing to mitigate the felt recoil of the firearm.”

    Should it not say “Compensators and FLASH HIDERS……….

    Great article by the way.

  11. avatar Jerry McFadyen says:

    Thanks! Very well done and helpful article.

  12. avatar Jason Chester says:

    Range and accuracy will also vary between different types ammo so its best to test your rifle or handgun with different kinds of ammo and find which get you the best results.

  13. avatar George Steele says:

    Ah’m a-skeered to shoot ma gun in the living room, less’n the guvamint confiscate my house as a silencer . . .

    At some point, I think we all need to tell the “authorities” to butt out of things to which they have not been constitutionally franchised to attend. After all, the silencer was really banned not because of its use by criminals, but because landowners were afraid during the starving days of the depression that it would facilitate poaching – when harvesting game was an important source of nutrition.

    The fact that the above posts almost immediately drift from the issue of the physics of the interaction of post-combustion gas on visibility and transferred energy into whether or not you can get arrested for a secondary consequence of the design shows just how wary we have been trained to be of the government – when it is the government that should be wary of citizen retaliation when it oversteps its authority. A sad commentary.

    This discussion and analytical attempt to refine terminology is a good example of the kind of precise thinking that helps us in thinking through the dynamics of the shooting process. I think what most shooters would prefer is well-embodied in a Mag-na-port; directing unburned powder and excess gases both up and away, through ports in the barrel oriented about 45 degrees up from horizontal. That puts flash and gas energy upwards and outwards, minimizing flash obscurity on the line of sight, deflecting muzzle rise, and not pissing off the guy next to you on the firing line. It also somewhat reduces rearward-directed, gas-jet recoil.

    It may be that a hybrid device – God only knows what it would be called – that provided for encapsulation of ejected unburned powder until combustion completed, while directing the gas energy both up and to the side, would cover the principal objective, which is to make the gun more controllable in firing – both dynamically and functionally. It may also incidentally be that such a device would partially reduce the on- or off-axis noise level of firing. But if that is not the primary purpose of the device, then it should be defensible in both principle and practice from government overreach.

    I have heard it said that in Europe, NOT using a silencer when shooting or hunting is considered impolite, owing to the disturbance caused by the noise. Of course, the spaces there are not generally as wide open as here in North America. Interesting point of view, nonetheless, and a more mature attitude in regard to this one singular aspect of shooting. Not to say that some of them aren’t a little nuts when it comes to gun ownership . . .

  14. avatar MikeyMikeRN-BSN says:

    Could I impose upon you fine gentlemen to bestow upon me your infinite wisdom regarding the effects a 5.5 inch muzzle brake may, or may not have, on the ballistics of a bullet out of a 10.5 inch barrel? Can it affect performance of the weapon? Weapon in question is a SR556 that I occasionally run a custom 7.62×39 upper on that is purpose built around the 10.5 inch barrel.
    All feedback/advice appreciated.

  15. avatar Steve says:

    Actually, the first pic is a flash suppressor, not a flash hider. Flash hider’s are the snow-cone shaped dohickies made for M2 carbines & M2 machine guns.

  16. avatar Chris says:

    Not to nitpick, but I do hate the perpetuation of myths and pseudoscience. This is just in regard to the way that muzzle flash and flash hiders actually work.

    The myth is that remaining powder that has not ignited inside the barrel is blown out and ignites once it exits the muzzle. This actually is not logical at all. If it hasn’t ignited due to the 3,000 degree temperatures and 30,000psi or more inside the barrel, it won’t ignite once it is being rapidly cooled and depressurized once it has exited. No. What causes muzzle flash are the gases produced by the deflagration of the powder inside the barrel. In the barrel, there is very little to no atmospheric oxygen and so those gases cannot ignite. On exiting the barrel however, they mix with the atmospheric oxygen and are ignited by a combination of the shockwave (producing high pressure, and therefore, high temperature) and any residual sparks. This is why you see the flame appear several centimeters or inches out in front of the muzzle. this has been studied extensively by the U.S. Army in the 40’s and 50’s and there is paper describing it. Their solution to reduce flash with regard to artillery and big guns is to incorporate a flash suppressant (usually a salt of some description) in front of the powder or built into it. This insulates the gases from the oxygen and neutralizes some of them on exiting the muzzle, allowing them to cool and disperse without igniting. Powder usually burns completely within the first 1-6 inches of barrel, depending on burn rate. This is why, the shorter a barrel gets, the more flash you see. The remaining gas pressure diminishes the longer the barrel is and the more dispersed the gases are within it. therefore, less pressure = less shockwave pressure, less heat, less gas, therefore, less flash. If you shorten the barrel, the muzzle pressure goes up and the gases are more dense, giving more flash. If you want to see powder still burning as it exits the barrel, all you need to do is shoot a black powder pistol with a big charge of real black powder.

    As to flash supressors, the reason they are a “cage” shape has everything to do with breaking up the supersonice shockwave and disrupting oxygen flow to the muzzle, giving time for the gases to cool. Muzzle brakes and compensators also reduce flash due to this property.

  17. avatar Jim H says:

    So perhaps this question could justify a “part 2” to this exceptional article: how do blast shields factor into this? I’m no physics major, but if a blast shield is put over a muzzle brake, does it cancel out the recoil reduction? Also, what about linear compensators, which appear to be a combination of the two? Can they honestly claim to offer recoil reduction?

  18. avatar Jimmy aka Brandt says:

    Maybe I missed it but is there a flash hider / brake / compensator all in one device? And if so, is it effective enough to cover each need?

    1. avatar Andrew Lews says:

      That’s called a suppressor.

  19. avatar Fidel says:

    Ok, the main purpose for me to get an AR 15 is going to the shooting range ,so please what is your recommendation in order not to bother other shutters with a noisy rifle ,and at the same time reduced the movement ?

  20. avatar Memo A. says:

    Do you know if anyone makes a device that covers the barrel but also serves as a recoil reducer or flash hider? Fairly new and I am looking for a combo for an AR10.

    1. avatar Eberhardt Huhn says:

      Change your barrel to a longer one. That will burn all of the gasses before they exit the barrel. 24 inches would be more than enough to eliminate any flash from the end of the barrel, even without a flash suppressor.

  21. avatar Joeg Voll says:

    Excellent Article. I’m a novice, more concerned with the legislative aspects of weapons. Very well written, succinct explanation of an often confusing topic. I’m saving this site as a go to source of information. Thank You. joegv.

  22. avatar OldLawProf says:

    A flash hider hides the flash (and vision impairment) from the shooter.
    Nothing can hide it from those at the target although distance eliminates the vision problem. For them, it is just an extra 1-2 inches of unrifled barrel extension.

  23. avatar BobbyJ says:

    They are all the same thing just tuned differently. The names are changed to protect the innocent.
    Compensator – reduces barrel jump + recoil + adds noise
    Muzzle Brake – reduces barrel jump + recoil + adds noise
    Flash suppressor – same.

    They just move the holes around to change the tuning of where the gases escape. If they ports are at the top then it will push the barrel down after each shot, but it will also mitigate some recoil too.

    You can’t make one without it reducing recoil some. Its just simple physics at work. They change the name so the buyer knows what it is tuned for.

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