Home Forums Hunting & Shooting Gunsmithing Muzzle brakes vs. perceived noise

There's been noise complaints from a newish housing estate near our range. We've had to monitor and record the sound levels at various points outside the range boundary. During equipment setup we had the chance to do spot readings and one of our guys has a 375H&H with removable brake. No difference to the sound level at distance between with or without brake. Different story for those at the firing line of course.

I think the closest monitoring point was about 500m away.

So the general consensus is that it isn't any loader in any way aside from those who are on the firing line.

I believe so. The redirection of the gases by the brake directs more of the sound back towards the firing line than without.

I think you would experience brake level sound level if you stood off to the side but in the front side of the muzzle of an un-braked firearm, but I wouldn't recommend it.

Wrong: If it is louder on the firing line, it is louder in every way, the decibels don't just disappear. Any reduction depends on what is being braked, how far away one is, their relative position and obstructions. But the sound will still be more noticeable.

Hear a muzzle braked .300 Jarrett and you won't have to be on the firing line to notice.

Well we actually measured it and there was no difference at a distance, but if your opinion is better than fact, power to you bro

It sure as hell isnt perceived with my ear drums split.

What distance and what cartridge,which way was the wind blowing, same elevation, what testing equipment?

Decibels are decibels. I may not hear a piper flying low over your house a block away, a fighter yes.

The statement was it isn’t any louder in anyway other than. Facts are it is louder in every way.

Good question - I don't have all the answers. The range is the Belmont Rifle Range in Brisbane. The new suburb is an extension to Carindale. I don't have details of the test equipment or the testing organisation but it was to the satifaction of the EPA.

There were several test points with the closest being around 500m away from the range boundary. There were several monitors installed in the area for a period of time (a week?), so variable winds and different elevations but otherwise stationary at those points. The range is a public range so everything the public drag down there should've showed up during the testing. 50cal and the various 416 derivatives (416 Cheytac?), and the 338 Lapua are not allowed to be used on this range due to the "danger template" that has been approved for this range.

Our group, Big Game Rifle, has been labelled one of the main offenders for noise, and we have been proven guilty thanks to the testing. Our group shoot once a month and the testing technicians happened to be at site so that we could correlate our bangs with that being measured. We took the opportunity to check the 375 break and break-less, as that had also done with smaller cartidges from the bench (smaller being the 300WM - these are common and often braked in their tactical package). No difference at distance braked or un-braked.

We typically shoot 375H&H, 458WM, 416Rigby, 500NE & 505Gibbs as standard at our shoots, so we made the meters flicker a bit.

I haven't seen the report but have been told by club officials of the findings. Brakes can continue to be used except there are areas on the range where they can't be used but only to limit to noise coming back to the shooters and the main office.

Noise comes from energy and you need more energy to get more noise. Brakes just distribute at the firing line - the net result at distance is the same.

No doubt distance is your friend when it comes to noise and as the distance increase it become more so. Which should be an obvious. Distance is why I can’t hear the piper over your house from mine. What that distance is would be relative to the original decibels.

As far as your energy theory, the energy or noise as you define it, coming out of the muzzle is the same braked or not.

Read on:

https://precisionrifleblog.com/2015/08/07/muzzle-brakes-sound-test/

At some point you do get far enough away. However, that distance changes with the cartridge. Think.243W
vs .50BMG.

Still interested in your testing equipment.

Addition: question answered, thanks.

Addition 2: I have two gun clubs approximately 5 miles away. When conditions are right you can hear the cadence of them shooting trap.

Funny, I disagreed with battues reasoning earlier.
You have a set amount of energy, it's the distribution...

But then I considered an automotive muffler.
It turns noise energy into heat.

Energy, redistributed.

So, could a brake, allow more sound to be emitted from
the burning gas energy?

Or the fireball when that hot gas hits oxygen?

Suddenly, I know less.

Don't know the meters but they were good ones - the same type that EPA use the data from when they take people to court.

That testing article you linked was done at close range (60 feet) and in 2 positions - to the side and behind where you'd expect the brake to increase the sound level.

We can't compare the results - our testing was at longer distance. The bulk of the test points would have been towards the front and side of the firing line.

The article address the same:


“So you can theoretically use the inverse-square law to scale the sound measurements to whatever distance you’re interested in. In fact, there are calculators designed to do just that.”

You are absolutely correct with regard increased distance eventually negating the issue. However, shooters in relatively closer confines lack the advantage.

No.

There is no "controversy" about brake vs break for muzzle devices, only people who can spell and people who can't or don't care. The use of the word brake is to arrest, restrict, delay, retard, etc, just like brakes on a car. There are just as many people who talk about their car's breaks, and it's just as incorrect in that application too.

You don't seem to understand how a brake works, or vector analysis. Powder gas has both mass and velocity; that gas impinging against the baffles of the brake (calculate the perpendicular surface area if you want, that's what counts) is what causes a forward acting force that partially counteracts recoil. It's a fairly simple concept, and effectiveness of a brake is directly proportional to the amount of powder used; i.e. it's more effective with a light bullet and lots of powder than it is with a heavy bullet and smaller powder charge.

show me where the de-celeration vector is (definition of braking), please review your thermodynamics and the basic recoil equation again.

not saying that there isn't an effect, just negligible , and as I said previously the amt. of recoil reduction percentage is a ratio of the powder to ejecta total mass.

in a rifle as an example, the pressure is down to say, around 20k psi and velocity curve is almost flat. On exititing the pressure has dropped considerably more, and that reduced pressure (velocity of particles in gas) now occupies a volume that is around 100 times greater.as the volume, changes according to PV=P'V' before contacting any baffles.

some brakes/breaks, are angles back toward the shooter as in the fifty calibers, but the ration of powder to total ejecta mass is considerably higher than other caliber/powder combinations so is it the increased powder mass or the angles?

Etoh - you're making a very simple concept way too complicated. I already explained it for you, it is not any more complex than that.

A muzzle brake works the same way as the sail on a sailboat. Mass and speed of the air (wind) against the area of the sail.

Had a guy show up at the range with some sort of AK variant, with a muzzle brake, and start doing mag dumps.

I can take a few rounds without issue, but when somebody starts blasting mag after mag from a braked barrel, I get annoyed.

Sorry but your explanation is inadequate. the sail is affected by a continual stream of force, called thrust, there is no thrust component in this model

as you show no negative vector how about a negative scalar in the model. (decrease in gun recoil velocity) any amount is solely do to a subtraction of the ejecta amount.

any effect on baffles is do to (in most cases) the supersonic shock wave front hitting it, and while it has an impulse their is no thrust component. Thats why they are "louder" on the sides.

Take the case of "porting" recoil reduction with no baffles. MagnaPorting, shotgun porting, any baffle is the rear of the bullet or wad. And in particular when the ports are on the top of the barrel.

Do flash suppressors work with a solid bottom as muzzle breaks (intentional use), yes, by re-directing the gas/ejecta they change the torque moment, and effect muzzle flip, but no baffles are involved, simply an arithmetic subtraction of some of the ejecta.

In most cases adding front wt. on the end of the barrel has more effect than "relying on gas re-direction (breaking)"

Calculating the recoil in a shot fired is straight forward, and the wt. of the powder is added to the projectile wt.

subtracting the powder wt. gives the value the powder adds to this and the theoretical upper limit that can be used in any given caliber/bullet/powder combination

higher ratios of powder to projectile give the impression that this combination makes the compensator work more "efficient". This concept doesn't even include the gun weight, how can it be an across board comparison?

ex. 45 acp powder contribution 5/230 or .02% gun wt around 2lb

50 cal 250/800 around 30% gun wt. around 30 lbs

The science of it all notwithstanding, when a clown sits down next to me with a braked magnum (or even a braked 6.5 CM) I pack up and leave if I can't move to a bench far away from him. Aside from the re-directed noise, the re-directed concussive blast is also un-nerving- especially when I'm trying to work up loads for a light rifle and cringing while waiting for the next bench-clearing blast of hot gasses. My last encounter was with a clown shooting a braked Ruger tacticool chassis rifle of some sort in 6.5 CM that confirmed my take on the whole business. (And he wasn't hitting squat with it anyway.)

Use of brakes is entirely a guy's own business, his well earned right- up until he makes a nuisance of himself with it at a crowded range. It's no different than the kid with a loud hot rod, or an un-muffled Harley, who revs his engine needlessly in a quite residential neighborhood on a Sunday evening- inconsiderate at best.