Questions about muzzle breaks and harmonics

Discussion in 'Big Stuff -- 6.5mm, 7mm, 30 Cal' started by Kenneth66, May 24, 2018.

  1. Kenneth66

    Kenneth66 Silver $$ Contributor

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    I have had some experience with Tuners , but they are generally much larger than a muzzle break . Will the muzzle break such as a Gentry , affect accuracy one way or the other to a significant degree . Would it be feasible to stack washer shims in behind the break to move it out a little at a time to see if there was a sweet spot ?
    Or do you think I'm worrying about something that would only show any significance in a bench gun accuracy ? I have a Vangaurd in 300 weatherby magnum that I am going to put it on .
    Thanks , Kenneth
     
  2. Park ranger

    Park ranger

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    Isn’t tuners for non reloaders and 22 rimfire?
     
  3. Ledd Slinger

    Ledd Slinger Gold $$ Contributor

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    Some brakes offer a certain degree of tunability. Not as much as an actual tuner brake of course.
    The Chistensen Arms side baffle brakes offer tuning if the muzzle rise and have shown to be effective in reviews.
    https://christensenarms.com/product/titanium-side-baffle-brake/

    I am having an Area 419 Sidewinder installed on a new build. It does not have top port muzzle rise tunability, but offers adjustable indexing.
    http://www.area419.com/product/sidewinder/

    I'm personally not a fan of the crush washers, but I suppose they could help to tune a brake a little bit when used in the manner you described.
     
  4. Kenneth66

    Kenneth66 Silver $$ Contributor

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    Rimfire has been my experience with them , but have seen them in IBS score matches .
    But it had been a few years since I have been to one , can't remember if the top shooters were using them or not .
    Thanks for the responses and links .
    Kenneth
     
  5. dkhunt14

    dkhunt14

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    I doubt you will see much difference with that Vanguard. Probably better off with a rubber vibration thing on barrel like a Simms. Matt
     
  6. carlsbad

    carlsbad Lions don't lose sleep over the opinions of sheep. Gold $$ Contributor

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    A muzzle brake is more than large enough to affect your tune. Generally, if you do load development with a brake, it will be different if you take the brake off. The brake is large enough to take you thorough several cycles of tuning.

    -Jerry
     
  7. Zero333

    Zero333 Gold $$ Contributor

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    I've developed loads with out a brake. Then after i installed a brake the accuracy either stayed the same or got better.
     
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  8. ebb

    ebb

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    Only accuracy problem I ever had with brake was when it got loose and I didn't know and continued to shoot.
     
  9. RGRobinett

    RGRobinett

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    Harrell's Precision makes a decent combination tuner/brake - I've experienced good results using them on 7DAKOTA and
    338EDGE rifles.:) RG
     
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  10. 4xforfun

    4xforfun Gold $$ Contributor

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    In my 1st year of 1000BR (2008) I had only one gun ....my 300 WBY. In 2008 , Breaks were NOT ALLOWED in the HG class. Right before the last match in Iowa I looked at all my targets for the year and noticed that my HG 10 shot groups were about the same size as my LG groups. So, I decided to shoot the last LG match of the day W/O the break. Shot a 2.7xx...my smallest group , ever, by far at the time. My HG target backed that up...sorta.....9 in about 3 inches and a 15" flyer. BBL was toast or a bad bullet...don't know.

    I drug that bbl out for an F Class match a coupe years ago...no breaks in F class, and it was a hammer in testing...the shooter....not so much.

    Moral of the story....add or remove that big old chunk of steel hanging off the end of the BBL and your groups WILL change.

    Tod
     
  11. carlsbad

    carlsbad Lions don't lose sleep over the opinions of sheep. Gold $$ Contributor

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    If you're talking about tuning, then the harmonics of the barrel are affected by a weight hung on the end. When you add a weight the size of a brake, the tuning will be affected by as little as .oo1" of tightening. It will only take about .005" to .020" movement to take you thorough an entire harmonic cycle and get back to the next "zero". throwing a brake on will land you somewhere on the sine curve that describes the harmonic behavior. If you land at a multiple of 360 degrees, or to a lesser degree, a multiple of 180 degrees, then you won't change anything. This would be called lucky. If adding a brake improves accuracy, it probably landed on a node. If it hurts accuracy, it didn't.

    Nobody is saying a muzzle brake adds or detracts from inherent accuracy if properly installed).

    If adding and removing a muzzle brake does not affect your accuracy, then either you are getting lucky, or you aren't shooting groups small enough to notice the effect of the tuning. Tuning is the last .1 to .4 MOA below .5 moa accuracy.

    --Jerry
     
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  12. Bart B.

    Bart B.

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    Is not the objective of "tuning" with a moveable weight near the muzzle to change the muzzle axis vibration frequency so bullets leave on the best part of its upswing so slower velocity ones leave at the right angle above LOS and their greater drop at target range is compensated for and strike the target where the faster ones do?

    If so, then leaving 180 degrees away on the cycle would reverse that positive compensation and group will be larger vertically.

    I don't think you could change bullet exit 360 degrees on the whip cycle moving it .020 inch. And even 180 is doubtful. What's the vibration frequency vibration period compared to barrel time of .0012 second?
     
    Last edited: May 28, 2018
  13. gunsandgunsmithing

    gunsandgunsmithing The best tuners and wind flags on the market

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    I will say that there are several factors involved to come to that conclusion, like tuner weight, location, thread pitch, and barrel stiffness. My tuner lowers the frequency that a barrel vibrates at by a very significant amount, measured. Just adding mass alone does a lot of this, as does the particle dampened design. It only takes a few thou tuner movement to move the tune up and down a node wave. Add to that, there are many more forces upon the barrel under pressure, than just it's natural frequency at a given temperature.

    That said, I work up my initial loads with the tuner on the barrel. It just makes sense, right? It does work but it also seems to work to develop a load without the tuner on the barrel at all.

    How can that be? That question has been above my pay grade to figure out, yet.
     
  14. carlsbad

    carlsbad Lions don't lose sleep over the opinions of sheep. Gold $$ Contributor

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    Bart,

    (warning, long discussion including basic trigonometry. Stop reading now if this offends you).

    I've never taken high speed photography of a barrel and I've never calculated the natural frequency of a 30" HV barrel, but it wouldn't be too hard and I'm sure it has been done. But I have a lot of experience with harmonic oscillators and some experimental data using Mike Ezell's tuners so I'll post what I think I understand.

    If every round was the same, then tuning wouldn't do anything. It wouldn't matter where the muzzle is or what motion it is in since it would be the same for every shot. But rounds aren't identical. So what you want to do is minimize movement of the muzzle at exit. Most people would think you want the muzzle at neutral, pointed straight, but that is actually when it is moving the fastest. It has to stop at each extremity as it changes direction and that is when it is moving the slowest. You also don't know what plane it is vibrating in, up and down or left and right, or a combination of the 2. Lets use up and down for this discussion.

    As you tune the load, by moving the weight .001" per group, you find a place where the groups get better within .005" in my experience (each mark on the Ezell tuner is .001"). Now all you know is that it is better grouped. So you don't know if you're at 180 or at 360 (up or down). You can keep going another .005" and see which node makes a better group. But I don't. I stop and call it good.

    As an aside, the sine wave I used in my previous post is actually a cosine wave since cos 0=cos 360 =1, cos 180 = -1. Both of these extremes represent the stopping of the barrel as it reverses direction. Also, if you look at the cosine wave, you see it gets almost flat for a while near the top. That is the best place to tune to. Of course we do it experimentally so you don't really know where you are, just that the groups are smaller.

    So in summary, as I understand it, the 180 and the 360 should be the same for tuning.

    As for how much it takes to tune, I know from experience it only takes a few .001's of an inch with ezell tuners. I use big brakes (if a little brake will do it, then I just forgo a brake) that weigh similar to the ezell tuner so I'm thinking .005 to .010 will take you at least to the nearest node.

    --jerry
     
  15. Bart B.

    Bart B.

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    No. I want the slower bullets to leave at higher angles to the LOS than faster ones. That happens only on the muzzle axis upswing. If bullets exit centered about the 360 (top) or 180 (bottom) degree point of the muzzle axis sine wave, half of them will leave at the wrong angle on the downswing. Barrel frequencies they vibrate at are fixed. There is a small spread in bullet barrel time caused by velocity spread and pressure curve shapes.

    Are you familiar with Al Harral's and Geoffrey Kolbe's web sites using engineering calculations showing bullet exit points on muzzle axis cycles?

    I know most of the muzzle vibration axis is in the vertical plane because the rifle recoil axis is above its center of mass.

    I have software to calculate a barrel blank resonant frequency . Most are at several dozen cycles per second. Bullets with a 1.25 ms barrel time are out in the time a barrel with an 80 Hz resonant frequency go through only 1/10th or 36 degrees of one resonant cycle. The 3rd or 4th harmonic frequencies thereof at several hundred Hz is what the muzzle axis vibrates at.
     
    Last edited: May 28, 2018
  16. Ledd Slinger

    Ledd Slinger Gold $$ Contributor

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