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Thread: Experience With Muzzle Brakes

  1. #1
    Boolit Bub
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    Jan 2012
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    Experience With Muzzle Brakes

    I thought I'd share an experience I had with muzzle brakes.

    A little while back, I threaded a rifle barrel for a muzzle brake, intended for use with a suppressor. I indicated the barrel on my lathe, using an insert in the muzzle to ensure the threads were cut concentric to the bore. The threads were cut to the muzzle brake manufacturer's specification, the critical dimension is the thread depth, at .600" (+/- .010"). Operation complete, brake installed, customer happy.

    Next time I talk with the customer I'm told he suffered a very mild baffle strike. Not good. Further information reveals that a rifle capable of sub 2 inch groups at 300 yards is now shooting 8" patterns at 100 yards. Not good. My suspicion is unstable bullet.

    I get the rifle in the shop and confirm the threads are good, shoulder is good, muzzle crown is good and muzzle is flat. The rifle, without the brake, shoots a stabilized bullet and a test group of .750" at 50 yards (I have a very small test range). Install the muzzle brake and it confirms an unstable bullet. Looking at the carbon residue in the brake it appears there is about .300" of exposed thread and I noticed about a .700" total gap between the muzzle and first baffle in the brake. What was happening is the air being pushed out of the barrel by the bullet (precursor wave) was being disturbed by the exposed threads and other irregularities in that .700" gap, causing turbulence that destabilized the bullet.

    My solution was to make a plug that threaded into the brake to take up that gap and eliminate the turbulence. After a bit of fitting I installed the brake and fired a test shot which revealed a stabilized bullet. A 50 yard group of .230" confirmed my solution.

    In the future, any threads I cut for muzzle devices will be cut based off measurements from the device to ensure no irregularities exist to cause turbulent air. I hope that any practicing gunsmiths can benefit from this info.

  2. #2
    Boolit Master


    Taylor's Avatar
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    Right on time with this,thanks.As I am preparing to thread and add a muzzle brake to a Mosin for my son.
    Pro Patria-Ne Desit Virtus

  3. #3
    Boolit Bub
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    Thanks for the information. This is great information and will definitely help me on several projects I am currently working on.
    Your knowledge and sharing of this is greatly appreciated.
    re

  4. #4
    Boolit Master
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    Very interesting... I'll keep that filed away for "someday".

  5. #5
    Boolit Master

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    I have been making brakes for about 20 years and at the beginning I set up a barreled action on a set of rails to test brakes. Several of the brakes on the market look great but do not reduce recoil. The design I ended up with has a free bore that is the miner diameter of the threads. The end of the brake has an exit hole for the bullet that is .020-.030" bigger than the bullet diameter. There are 42 holes at a right angle to the bore to redirect the gas. I tried slanting the holes forward 30 degrees and back 30 degrees. The holes slanted forward made for less noise but only gave 25% reduction in recoil. The ones slanted back did not have any more reduction than those at a right angle but were much louder to the shooter. The test action had a 22" 308 barrel and I was getting 50% reduction in recoil. The whole idea in a brake is to redirect the gas pressure so it does not cause recoil. Slanting the holes back does not pull the barrel forward as some have suggested. My brakes are 2.2" long with 1/2" being threaded and the end about .125" thick for the exit hole leaving a chamber about 1.575" long. There must be a lot of turbulence inside the chamber but it does not seem to have an effect on accuracy. Some of my customers like the brake turned down to the same diameter as the OD of the barrel which I believe hurts the effect of the brake. The wall of the brake needs to be thick enough to redirect the gas and a thin wall does not work as well. Most of the brakes I make are 3/4" OD and I taper the rear portion down to barrel diameter. I like to use the larges thread possible to keep the wall thickness of the barrel as thick as possible. If you have a 1/2-28 thread on a 40 caliber the end of the barrel can be distorted when the brake is screwed on tight. If the OD of the barrel is 5/8" I will use 9/16-28 so there is a shoulder for the brake to be tightened against. While I have used larger threads for large diameter barrels it is alway best to stay with a fin thread. A customer sent in a barrel with a brake that someone used 3/4"-16 thread and I found that every time the brake was tightened it had a different alinement to the bore. Threads on the barrel should be cut for a close fit to the threads in the brake. I have cut threads for cans and sometimes the can will not fit even tho a gauge will screw on. I alway request that the part that threads onto the barrel be handy so I can cut the thread to be a close fit.
    John Taylor, Taylor Machine, gunsmith

  6. #6
    Boolit Master
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    Quote Originally Posted by Taylor View Post
    Right on time with this,thanks.As I am preparing to thread and add a muzzle brake to a Mosin for my son.
    THeres a company that makes a muzzle break for mosin nagant rifles that attaches using the bayonet lug method. IT seems very nice, and in the videos a guy claims to shoot his weapon using 1950s Bulgarian heavy ball. From the shoulder and firing it one handed like a pistol the recoil seems the same.

  7. #7
    Boolit Master Tripplebeards's Avatar
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    I have a couple kdf brakes that work awesome for reducing recoil on my RUMs but every time I hunt with them and shoot my ears suffer. I shot my POF with the factory brake and one of my ears had blood in it and hurt for a week. I've learned not to purchase rifles with brakes anymore unless I wanted them pre threaded for a can.

  8. #8
    Boolit Master Nobade's Avatar
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    Quote Originally Posted by John Taylor View Post
    I have been making brakes for about 20 years and at the beginning I set up a barreled action on a set of rails to test brakes. Several of the brakes on the market look great but do not reduce recoil. The design I ended up with has a free bore that is the miner diameter of the threads. The end of the brake has an exit hole for the bullet that is .020-.030" bigger than the bullet diameter. There are 42 holes at a right angle to the bore to redirect the gas. I tried slanting the holes forward 30 degrees and back 30 degrees. The holes slanted forward made for less noise but only gave 25% reduction in recoil. The ones slanted back did not have any more reduction than those at a right angle but were much louder to the shooter. The test action had a 22" 308 barrel and I was getting 50% reduction in recoil. The whole idea in a brake is to redirect the gas pressure so it does not cause recoil. Slanting the holes back does not pull the barrel forward as some have suggested. My brakes are 2.2" long with 1/2" being threaded and the end about .125" thick for the exit hole leaving a chamber about 1.575" long. There must be a lot of turbulence inside the chamber but it does not seem to have an effect on accuracy. Some of my customers like the brake turned down to the same diameter as the OD of the barrel which I believe hurts the effect of the brake. The wall of the brake needs to be thick enough to redirect the gas and a thin wall does not work as well. Most of the brakes I make are 3/4" OD and I taper the rear portion down to barrel diameter. I like to use the larges thread possible to keep the wall thickness of the barrel as thick as possible. If you have a 1/2-28 thread on a 40 caliber the end of the barrel can be distorted when the brake is screwed on tight. If the OD of the barrel is 5/8" I will use 9/16-28 so there is a shoulder for the brake to be tightened against. While I have used larger threads for large diameter barrels it is alway best to stay with a fin thread. A customer sent in a barrel with a brake that someone used 3/4"-16 thread and I found that every time the brake was tightened it had a different alinement to the bore. Threads on the barrel should be cut for a close fit to the threads in the brake. I have cut threads for cans and sometimes the can will not fit even tho a gauge will screw on. I alway request that the part that threads onto the barrel be handy so I can cut the thread to be a close fit.
    Gosh John, your experience mirrors mine. Been making brakes for about 20 years now, ours are the same other than 4 ports on the side and top, none on the bottom. I wish I could find somebody who could install them properly since it is almost a full time job doing them and I don't have time to do everything else in the shop too! No kids seem to want to be manual machinists for low gunsmith pay any more.

  9. #9
    Boolit Master Texas by God's Avatar
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    I'd wager shooting a braked rifle without hearing protection is worse than standing ten feet from the stage at a rock concert. I've never owned a rifle that needed one but I know people that do. 30-378 Weatherby comes to mind.

    Sent from my SAMSUNG-SM-G930A using Tapatalk

  10. #10
    Boolit Master tazman's Avatar
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    Quote Originally Posted by Texas by God View Post
    I'd wager shooting a braked rifle without hearing protection is worse than standing ten feet from the stage at a rock concert. I've never owned a rifle that needed one but I know people that do. 30-378 Weatherby comes to mind.

    Sent from my SAMSUNG-SM-G930A using Tapatalk
    For me it is anything larger than a 30-06.

  11. #11
    Boolit Master

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    I do threading for brakes and re do botched jobs and some of the guns have really boogered crowns on the barrel. I had one in the other day that was all just rough splinters where they threaded with a dull tool and screwed the brake on with a wrench. When I install I thread the barrel and then do a flat crown and then fit the brake tight inside and out on gap on the inside. Never had one come back.

  12. #12
    Boolit Master
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    brakes will increase noise for the shooter, its how they work, redirecting all that muzzle blast backwards. Compensators like the spikes tactical dynacomp are amazing in my opinion. at least for me it makes my short barreled .308 ruger amaerican predator sound duller in volume and sharpness and less muzzle lift and recoil.

  13. #13
    Boolit Master
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    I once owned a barrel with a brake/break. No it was not broke.
    Brakes belong on vehicles, IMHO.
    I am no he man, nor am I stupid. Shooting from a bench, a 30-378 will wake you up to say the least. Do that with a 460 or 458 Lott with full throttle loads. I still say a 416 was the worst I ever shot.
    Shoot those same whopper stoppers from a standing position is way more comfortable.
    I have to wear plugs and muffs, good ones! In order to even function around guns with "amplifiers" on them. The concussion goes into my sinus as well.

    I have yet to see a brake fix a flinch from recoil.

    Not knocking those folks that like and use them at all. Just watch how it will clear a firing line in short order.

  14. #14
    Boolit Master Texas by God's Avatar
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    A local gun store had a NEF pardner .300 Blackout with a .50 BMG type chevron brake on it. WTH.....I chuckled and shook my head at the tacticluelessness of it all.

    Sent from my SAMSUNG-SM-G930A using Tapatalk

  15. #15
    Boolit Master

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    The best thing I found about the muzzle brake on the Ruger .450 is that it's removable.


    We accumulate our opinions at an age when our understanding is at its weakest. Georg C. Lichtenberg

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