Gunsmithing Free Muzzle Brake

[Done Vida]

I joined a machine tool night class around a month and a half ago and have gotten to know a couple of guys that have been in the day class for awhile. They are gun guys and as a side project during the night class they have been making muzzle breaks for AR type rifles. They have a few designs that look pretty cool. We got to talking the other night and they offered to make a .30 cal. one for my bolt gun. My question is what tolerance should there be for the round to pass through with out affecting accuracy or being dangerous? Also, for the brake to be effective and not just an ornament on the end of my rifle, what angles need to be cut in the ports? Is there a certain degree that is the sweet spot? Any thing else I should be weary of or need to measure for safety before I fire any rounds with it? I wanna make sure all is well before put it on a rifle I've spent a lot money and time on. Thanks for any input.


Vida

 

[DAVETOOLEY]

.020" a side minimum and don't angle the ports to the rear. That just makes them obnoxious. You could even angle the rear wall a few degrees forward.

 

[Greg Langelius *]

Dave, I don't know if you're the person to ask, or even if such a person exists, but here goes.

Seeing your use of the word "obnoxious", I gather that you have concerns about brake noise, and consider it possible to moderate it somewhat. I think that can be followed up upon somewhat.

I see the brake as functioning by redirecting the reaction thrust from muzzle blast.

My thoughts are that this thrust loses velocity/effectiveness as it expands with distance; but the pressure waves the initial venting creates remain as obnoxious sound levels. I think that at some point, those waves can also be redirected without rendering the braking ports ineffective. I'm not trying to suppress, baffle, or in any way attenuate those pressure waves; just to redirect them in a more benign direction.

I've worked with rockets and think there are some similarities here. BTW, if those braking ports were configured as divergent cones, with respect to expansion ratios based on muzzle pressure/ambient pressure differentials, they might be made to work more efficiently. Such conical ports could be angled rearward for more recoil attenuation while the cowl might redirect/negate some/much of the resulting rearward sound pressure wave.

I expect that a 'cowl' could be erected an inch (or several) outboard of the the brake ports, that can be blocked in all directions except forward. If the ports and cowling(s) were restricted to cover only the sides of the muzzle/brake, optical axes would not be obstructed, and dust blast signatures might also be reduced.

Thoughts? Others as well?

Greg

 

[dang472]

Armalite uses a deflector to direct the blast coming off the first angled port of their AR50 brake.

 

[Greg Langelius *]

I see that now, thanks for the images, etc.

I think it's a rudimentary approach that could be carried a lot further along the lines I'm suggesting.

I also think that the volume of gas released by a .50BMG discharge could make the required dimensions/mass kinda huge. Such a cowl would need to be sturdy, or the blast wave might fatigue it and eventually turn it into shrapnel.

Greg

 

[Done Vida]

Thank u guys for the replies. Apparently I'm in a little over my head here lol. So in short as long a there is .020 clearance min. I should not be worried about putting it on my rifle? What about port size? Is there a min. So that the gasses can vent properly?
Thanks


Vida

 

[Greg Langelius *]

I apologize for the hijack...

Greg

 

[DAVETOOLEY]

Thank u guys for the replies. Apparently I'm in a little over my head here lol. So in short as long a there is .020 clearance min. I should not be worried about putting it on my rifle? What about port size? Is there a min. So that the gasses can vent properly?
Thanks


Vida

Vida

Sorry to hijack your thread. To a point the larger the better. Sidewalls can't get to thin or you'll blow the end off the brake.

 

[T2CH]

A brake that is not properly built or timed correctly (in the case of a non 360 degree design) can impede accuracy.

I have also seen brakes that broke apart from the blast because the there was not enough material between the ports. Be careful...

 

[Done Vida]

No worries on the high jack ( I didn't even look at it that way). It's all good info and stuff I am enjoying learning.


Vida

 

[DAVETOOLEY]

Dave, I don't know if you're the person to ask, or even if such a person exists, but here goes.

Seeing your use of the word "obnoxious", I gather that you have concerns about brake noise, and consider it possible to moderate it somewhat. I think that can be followed up upon somewhat.

I see the brake as functioning by redirecting the reaction thrust from muzzle blast.

My thoughts are that this thrust loses velocity/effectiveness as it expands with distance; but the pressure waves the initial venting creates remain as obnoxious sound levels. I think that at some point, those waves can also be redirected without rendering the braking ports ineffective. I'm not trying to suppress, baffle, or in any way attenuate those pressure waves; just to redirect them in a more benign direction.

I've worked with rockets and think there are some similarities here. BTW, if those braking ports were configured as divergent cones, with respect to expansion ratios based on muzzle pressure/ambient pressure differentials, they might be made to work more efficiently. Such conical ports could be angled rearward for more recoil attenuation while the cowl might redirect/negate some/much of the resulting rearward sound pressure wave.

I expect that a 'cowl' could be erected an inch (or several) outboard of the the brake ports, that can be blocked in all directions except forward. If the ports and cowling(s) were restricted to cover only the sides of the muzzle/brake, optical axes would not be obstructed, and dust blast signatures might also be reduced.

Thoughts? Others as well?

Greg

Greg,

It's not the noise that bothers me. It will always be there. It's the air put in motion by the expanding gases. It's a two part impulse. The supersonic boom coming off the bullet and then the shock wave from expanding gases.

I understand what you're suggesting. I see no reason why it wouldn't be beneficial. I question, when do you reach the point of diminishing returns that makes it not very practical? There are very minor things that can be done to the ports on a brake that can control the shock wave caused by expanding gases. I've seen high speed video of a brake that manages gases very well. I've also observed an interesting pattern in the sand after being shot 40 times prone. The initial sound wave is circular and is not affected directionally by the baffling in the brake. That's from the bullet. The influence the baffles have seems to be entirely on the expanding gases and as I said it doesn't take much modification to make a difference in the felt concussion.

 

[DAVETOOLEY]

A brake that is not properly built or timed correctly (in the case of a non 360 degree design) can impede accuracy.

I agree with the not properly built part but indexing has nothing to with accuracy. The bullet is gone before the gases have an affect on the barrel via the brake. Almost all brakes are balanced in their port area. Thus offsetting equal forces.

 

[mcfred]

.020" a side minimum

Per side, or on the diameter? I've always used 0.020" on the diameter (0.010" per side) based on this article:

Adventures With Muzzle Brakes | RVB Precision

 

[dang472]

This is from my gunsmith Nathan Dagley on his muzzle brakes....Facts: muzzle brakes are NOT for everybody as they do increase noise for the shooter, but they are very effective at reducing recoil. I believe there is no brake quiet enough to shoot without hearing protection, so I designed my brake for maximum efficiency.
Our "V" port 10-degree brakes are designed to vent out the sides at a slightly up angle, stopping dirt and debris from being blown up when shooting prone (or from a bench). This design also prevents noise from deflecting off the ground back toward the shooter.
Our brakes are made from 416 Stainless Steel, a highly machinable and heat-treatable steel. Most all stainless match barrels are made from 416R.

Straight Shot Gunsmithing

I've read on these boards that usually the first 2 ports handle the majority of the gases and the 4-plus port muzzle brakes are mostly cosmetic/gimmicks.

 

[Greg Langelius *]

Thank you very much for your helpful, thoughtful, factual reply, Dave.

You've brought more to the table than I had considered initially. I see new (to me) complexities.

As to at what point, etc., I imagine there's only one way to find out, and that's to put it to some tests. I'd love to have the resources, but they are at present beyond my means.

But I never give up on an idea, even of I may have to wait for additional developments to pave a better way. As always, I lay no claim to intellectual property for this or any other ideas I put on the 'Net. If I've put it out there, then it's out there, and fair game for goose and gander, alike. I'm about getting things done, and not about laying claims.

Greg

 

[T2CH]

I agree with the not properly built part but indexing has nothing to with accuracy. The bullet is gone before the gases have an affect on the barrel via the brake. Almost all brakes are balanced in their port area. Thus offsetting equal forces.

That's what I meant, wrong choice of words and hence the wrong meaning of the statement.

 

[Turd in the Pool]

Years ago someone came out with an aluminum cone that was meant to be installed between the brake and the bbl. to direct the gasses away from the shooter. Was a pretty good idea but looked obnoxious.

Vias hit a home run with his idea of drilling holes from the front. Might cost a little in recoil reduction but the trade off is worth it.