AR15 Muzzle brake effect on accuracy

One good group in a bunch of poor ones is a false positive. I have never had a problem with a muzzle break (cheap or expensive) affecting accuracy. It is certainly possible though.

Last year my dad bought a browning in 223 for my kids. We screwed a muzzle break on it and we noticed our 1" groups went to 6". Ended up leaving it off.

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if you are talking about a Browning BOSS muzzle break?

They are designed to be screwed in and out to fine tune barrel harmonics for best accuracy.

If you just screwed it on and didn't follow the instructions to tune it to the load you were shooting?

Poor accuracy could result.

rc

A lightweight, symmetrical brake shouldn't hurt accuracy *as long as it is mounted straight and is not loose*. However, a heavy brake could change the barrel harmonics some. A brake will make the rifle much louder, though.

An asymmetrical brake, like the old Russian slant brake on AK-47's, can hurt accuracy by causing bullet yaw leading to nutation.

The muzzle brakes i've had, have helped more than hurt, in my experience.

Anytime you hang a weight on the end of a barrel, it effects the harmonics. It can affect accuracy one way or another. Some benchrest shooters use adjustable muzzle devices similar to the Browning BOSS system to “tune” their rifles.

The only muzzle brake I have ever put on one of my rifles is a Surefire brake/adapter in order to accept a suppressor. Alone, it changed the point of impact about 1.25”, but the groups actually tightened up a bit.

With the suppressor added, the groups opened up a bit but still around .75 MOA.

You say you built your AR...have you double checked your barrel nut and gas block? Is your barrel free-floated? Is the muzzle crown damaged inside the break?

I usually don't see much change if any, but the one I built for my 10" .300 Blk had a serious negative impact, taking 5 shot 100 yard groups from 1.6" to over 4". And though it effectively reduced recoil, it also caused noticeable blast to be directed back at me. Back to the drawing board on that one!

Shame, too. It was a cool looking brake, IMO (second from left):

As mentioned, it can affect barrel harmonics. That in itself shouldn't make the gun any less accurate overall, but it could change the barrels "preference" for a load. It's kind of like a pendulum where there is an instant at the extreme right and left travel where the pendulum actually is not moving. At the bottom center of its swing it will have maximum velocity. To draw an analogy to a barrel, you'll usually see better groups of the bullets are exiting at on of the extremes in the whip where the barrel is not moving for an instant than if the bullet exits while the barrel is in fast motion. Adding the mass on the end changes that harmonic. So now loads it used to like might not be right for this "tuning" if you will, but loads it once disliked may be better suited (though some may just be flat out inaccurate or inconsistent).

Another factor, especially for inexperienced shooters, is that the increased blast can cause flinching.

Brakes aren't supposed to improve accuracy as much as tame recoil for the second shot to go off more accurately.

If screwing one on affects accuracy that much, then don't. Brakes are supposed to be neutral in accuracy - by taming recoil they let the shooter do his job a bit sooner, is all.

Given another second or two, the gun returns to rest and the second shot would be just the same MOA as the first.

Muzzle devices cover up and alter the shape of the end of the barrel - where the crown was originally shaped for most consistent exit dynamics, a break introduces a shoulder that alters it, plus channels the blast as the bullet moves away from the muzzle. How that happens is entirely up to how well it was machined according to engineering analysis, or at least some pretense of testing to make sure it doesn't alter things negatively.

Cheap brakes off Ebay? I see them for under $20, but you get what you pay for. In this case the A2 would be the better choice - it's been engineered, to say the least - and unless the shooter is qualified top ten percent in his class, he's not going to be able to take advantage of the assumed increase in accuracy. Said accuracy being in fast strings of fire, not paced range shooting.

Brakes have a purpose - side exiting brakes are for fast shooting AKA 3Gun, other than that, they are largely a dress up item, like 20" dub rims on a Cavalier. The results are often disappointing as the overall effect is much less than promised.

We are now right back to what the OP was relating - brake doesn't seem to do any good. Not unlikely at all.

Neither a .300blk nor a .223 should have that much recoil. I'd rather have a flash hider just because the brake blast can be so obnoxious for both you and shooters around you. A2 is a great design in that it's cheap and works well. Great bang for the buck.

Muzzle brakes or compensators CAN have a dramatic effect on accuracy. Look inside your brake and see if any copper is building up.

My friend had a high-end target pistol that was throwing flyers and we found lead build-up on the compensator, which was tweaking the bullet on exit.

The exit of the bullet is the most important time in the bullet's flight.

I have seen on several occasions, where the bullet has touched the parts of the muzzle brake with negative affect on accuracy.
Look carefully for copper smears or color with a lot of light inside the brake. You might find the cause of your accuracy problem.

If you really liked the brake, just try a different one. The nice thing about A2 flash hiders is that they won't kick up dust if you are shooting probe. That or the three prong would work fine though. But like I said, try a different brake if you prefer it. Sometimes you can find high-end products at low prices on CDNN. They had AAC flash hiders on there waaaay below typical market cost not long ago.

eldon519 said:

Neither a .300blk nor a .223 should have that much recoil. I'd rather have a flash hider just because the brake blast can be so obnoxious for both you and shooters around you. A2 is a great design in that it's cheap and works well. Great bang for the buck.

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I love the birdcage because of the advantage shooting prone (you don't eat nearly as much dirt), but the Smith Vortex is my go-to for muzzle flash.

It makes it go away completely.

This is a video of a lot of flash hiders tested on an 11.5" SBR (about the worst case scenario for muzzle flash)



When you get bored fast forward to the 5 minute mark and wait, you'll see the end of a muzzle break test, then immediately after the Smith Vortex (at the 5:30 mark).

Even on an 11.5" SBR, the flash is GONE. Completely frigging gone.

Those Smith Vortex flash hiders are the best out there, period.

I've put several on my guns - including changing out the factory compensator for a Smith Vortes on my SCAR17S - and I've noticed zero affect on accuracy or point of aim. (The SCAR shoots better with the SV flash hider than it did with the factory compensator by a fair margin)

Pull the muzzle device and shoot a group or two. That way you know for sure if it's the muzzle device doing this. If the threads aren't concentric, you can have a bullet kiss the muzzle brake and that could cause your accuracy issues. Pull the device and see what it does. If it improves put whatever flash hider you want on it.

I briefly had a Browning A-Bolt with Ballistic Optimizing Shooting System (BOSS) muzzle device used to tune the harmonics to best accuracy. Shooting up 7mm mag cartridge$ to fine tune the accuracy for a particular bullet weight was not my idea of practical.

More to the point of the opening post: my son had disappointing accuracy from a FAL. I noticed copper on one side of the opening of the flash hider. We remover the flash hider and groups improved dramatically once bullets were no longer swiping the flash hider on exit. (The flash hider was an aftermarket clip-on sold to restore neutered AWB compliant FALs to original appearance so removal was easy.)

While I have had problems with some muzzle attachments, the AR15/M4gery muzzle break/flash hiders I have seen and used don't appear heavy enough to affect harmonics and have clearance so as not to touch the bullet.

I don't have anything to add regarding a muzzle device but...

I thought my last shooting trip went OK...had a hard time getting zerod and that's never happened before...but last three shots grouped about 1.5 to 2" at 100.

This time 1" high. Next shot 3" left. Correct to 3" right. Bullseye. Next shot 2"left. Next shot not even on the target....next shot 2" high, 2" right...it went on like this.

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I had this happen to me with two different rifles. One was an old sporterized Lee Enfield with a loose rear (aftermarket) sight. Replaced it with a solid scope mount and the problem went away.

The other was an M16A2 (USMC issue). It usually shot pretty well, as long as I did my part. One day during a pre-qual, the rapid fire target looked like a shotgun blast hit it. I checked the gas rings and found they had aligned. Turned 'em around a little and it shot fine after that.