Mitigating Barrel Whip and Harmonics

[Canhunter35]

Shorter stiffer barrels have smaller nodes. The frequency of the barrel vibrations are shorter meaning the barrel doesn't stay in the upper or lower part of the swing range for as long. A palma barrel has a much wider node than a heavy varmint. The size of the node doesn't mean more accurate it means more forgiveness to your tuning. Larger nodes stay in tune way easier. Think of the short fat barrels on a ppc gun. Accurate as all get out but really hard to keep in tune.
Shep

Agreed, which is why I wrote it the way I did

 

[PNWdude67]

I'm deciding on a barrel contour for a hunting rifle build (300 PRC) and my research on barrels has brought to light the question of barrel whip.

We know that heavier barrels are supposed to be more accurate, but I wonder what can be done to mitigate the loss of accuracy as one goes with a lighter barrel.

I have a theory that fluting a barrel helps mitigate barrel whip. Any thoughts on this?

I also came across a strange contraption on Amazon: "LimbSaver Sharpshooter X-Ring Barrel Dampener." For $9.99, people are swearing that this thing is helping their groups considerably. Is this for real? Is it only helpful to light-weight barrels? Why would this be okay but having a floating barrel be so important?

 

[25WSM]

The OP specifically ask about barrel contours and whip and how to mitigate it. I believe he is getting excellent answers. Does a hunting gun need to be any particular contour. Depends. Guys I shoot 1000 yard br with shoot 20 pound guns of heavy tripods to hunt deer with well over a 1000 yards away. I personally would not want to try a 750 yard shot from field positions. And I'm not really sure how much barrel the op needs but I do believe he has gotten some very helpful info.
Shep

 

[25WSM]

Sorry canhunter I must have read it wrong from you then. My fault. I am on a hand full of drugs laying in the hospital waiting for a surgery. It's no excuse but it's true. I just had my hospital turkey diner. The chocolate milk I ask for was good.
Shep

 

[25WSM]

I only had issue with the first sentence. Sorry.
Shep

 

[PNWdude67]

As far as "tuning" barrel harmonics with the limb saver ring .... there have been some videos showing it does affect shot groups.... negatively ... there may be something to it for a specific load and the closer it is to the receiver the better it seemed to work. Rex Tiber does the best job of explaining the myths behind fluting...and he concludes it does not stiffen or help in any way with "barrel whip" compared to a smooth barrel of the same weight and length. I am a hunter who became a field match shooter to improve my rifleman mechanics and skill. We use heavy contour barrels and carbon fiber barrels for matches with gun weight restriction..my "test" that is not scientific but gives me confidence in the light weight carbon fiber barrels was: I recently had two match grade 7 mm M24 contour barrels chambered identically that were as accurate as one could dream of out to mile. I decided to have them carbon fiber wrapped by OMRC... they had 2.75 pounds of metal turned off them and shortened from 27.5" to 24"..... the shortening did cause about 75 FPS loss in velocity as expected. The accuracy to my pleasant surprise was absolutely maintained and they do not "walk" on 3-5 shot strings. In my opinion the diameter (that Rex talks about) of the carbon fiber wrap material maintained the integrity that the diameter of the metal removed did (if not increased)and the stiffness. So going forward my "less heavy" hunting rigs will sport large diameter carbon fiber wrapped barrels. As far as barrel whip and harmonics ... that's where load development comes into play and will always be the key to finding the most consistent load and understanding how your rifle system performs.

 

[keithcandler]

Limbsaver Ring helped groups in three of my sporter barrel rifles. As a former benchrest shooter, I know how to develop loads.

I developed the most accurate load for a specific powder and bullet, then went to using the ring. I started with the ring about 1/2" from the forearm tip, and moved it out in 1/2" increments. It was clear to see how the groups changed position, opening and closing up.

The thought did occur to me, " what would be the effect of using two rings"?

I also have the Mike Ezel tuner on a custom 6 XC, Harrells tuner/brake on 6 Dasher, and a RAS tuner brake on another 6 XC.

All the tuner and tuner brakes work in reducing group size. Custom rifles that shoot .250 groups go to shooting groups in the .070-.190 groups and less with tuners.

The Browings BAR in 270,30/06, and 7 Mag would shoot 3/8" groups or less for three shot groups and repeat, A bolts would do the same with the Boss system on them.

Tuners are just a concept that is not accepted because they are not understood. New ideas take a long time to take root.

 

[25WSM]

Guys at williamsport have some on their 1000 yard be rigs. I run Ezzels on my match guns. Varmint Al has some excellent articles on tuners.
Shep

 

[Susquatch]

Barrel harmonics, barrel whip, and vibrations of all types is a VERY complicated subject. WAY beyond what anyone can or should try to cover here. Don't forget that barrels (and other parts) can move in many dimensions and forms and harmonics. Bending up and down, sideways, whirling, twisting, and lengthwise (stretching). Each of these can be at different natural frequencies as well as multiples of these frequencies. If you ever get a chance to measure it, simulate it, or film it, you will conclude that it's a miracle that any rifle can shoot as well as they do.

Although light barrels can shoot exceptionally well, heavier barrels slow down the frequency of the vibrations and thereby widen the accuracy nodes - its plain old physics and cannot be refuted. Therefore, heavier barrels are easier to tune, less sensitive to other variables, and more consistent. As JE Custom said well, weight is your friend.

In my humble engineering opinion, it is impossible to eliminate vibrations. But, if absolutely everything about every shot is exactly the same as every other shot, every shot is much more likely to shoot the same as the other shots. It doesn't really matter if the barrel does a limp noodle whirly gig as long as each whirly gig is exactly the same as the others. In my view consistency (doing everything exactly the same each time every time, is everything. Heavier barrels help with that.

I will differ from other opinions on the subject of fluting. Fluting increases the cross sectional moment of inertia for equal weights. Therefore, a fluted barrel will behave and vibrate more like a heavier barrel than will a non-fluted barrel of the same weight. It also helps keep the barrel cooler by dissipating more heat than a non-fluted barrel can.

Some machinists also believe that residual stresses from the machining process are a problem. I have no facts on this aspect of fluting and therefore no opinion.

 

[TXAoudadKlr]

You can try having a longer shank then having the barrel tapper. Like 1.20-1.25" shank 6" long the taper to .830" @26"

Would be very stiff and lighter than a barrel of similar stiffness

 

[Bro Dave]

I'm deciding on a barrel contour for a hunting rifle build (300 PRC) and my research on barrels has brought to light the question of barrel whip.

We know that heavier barrels are supposed to be more accurate, but I wonder what can be done to mitigate the loss of accuracy as one goes with a lighter barrel.

I have a theory that fluting a barrel helps mitigate barrel whip. Any thoughts on this?

I also came across a strange contraption on Amazon: "LimbSaver Sharpshooter X-Ring Barrel Dampener." For $9.99, people are swearing that this thing is helping their groups considerably. Is this for real? Is it only helpful to light-weight barrels? Why would this be okay but having a floating barrel be so important?

You instigated a wonderful thread. thanks. JE Customs observation on fluting is right on.

Lets think about what we are trying to accomplish. This is a hunting rifle. You want to keep weight to a minimum while maintaining as much accuracy as possible. In reality you only need that accuracy for one shot or two. Three if you are having a bad day or multiple targets. What you really need is repeatable cold bore, first shot accuracy. A light whippy barrel will do that. I have a 6.5 PRC that I used for hunting this year and it performed beautifully with a light barrel. It will really start to walk on the seventh shot but I can get 5 solid accurate shots out before that happens. More than I will ever need in a hunting situation.

I do not have a tuner for the above reason but they do work or you would not see them on $7500 bench rest rifles.

 

[HARPERC]

.......I witnessed last week a guy who couldn't get his gun to shoot or tune, so he took a cereal box and wedges it into the front of the stock so there is excessive pressure between the front of the stock and the barrel and he immediately began shooting sub 2" groups at 600 yards

I've lost count of the rifles I've made a bench side correction in bedding with a folded target under the barrel at the fore end. One friend hunted, and shot several years with that folded paper in place.

When I'm feeling more "scientific", layers of electrical tape can be placed one at a time. Generally you will see groups tighten, and the open again when the sweet spot is passed.

I "THINK" for purpose of discussion any way we have to distinguish between harmonics, and the flex and whip of light barrels, magnum calibers, muzzle breaks, in stocks not up to the combination.

Sometimes issues are all in the stock. I bought a Ruger No.1, .30-06, light sporter, for a donor. Tinkered with it for education purposes, and it never shot groups. Wouldn't hold point of aim etc. Sent it off for a new synthetic, free floated, pillar bedded front and rear. Shoots so good I'm having a tough time going with rebarrel.

 

[25WSM]

Tune window all comes down to one basic component. Dwell time at the top and bottom of the barrel swing. I do use the word basic because yes there are a ton of other things that barrels do while being shot. You just can't say heavy barrels have bigger tune windows. I can assure you that a heavy short barrel does not have a wide tune window. Ask any short range br shooter how wide of a tune does a ppc barrel have. It's tune window is so narrow you need to tune it every 10 degrees of temp change or it won't shoot competitive. Now take my 300wsm heavy gun. It has a 34 inch 1.45 diameter barrel and you can drive a truck through that tune window. Same thing happens when you put a muzzle brake or tuner on. It slows down the muzzle speed so the barrel stays at the peak or the bottom longer. Bullets exiting anyplace that is not near the top or bottom are not in tune. Everything near the middle of the swing is bad because the barrel is swinging faster and over a greater distance. So again basically the slower your muzzle swings and the farther it swings gives you a greater tune window. If you make your barrel heavier and don't increase the stiffness it will have a wider tune. You make a barrel longer it will have a wider tune. A straight taper 1.250 barrel has a wider tune window than a hvy varmint of the same length. It's because the gain in weight is greater than the stiffness it gains and therefore swings longer and slower. Varmint Al has some of the most comprehensive test of this or you can talk to Mike Azzel for hours on end. Yes it's physics but you need to know what part of the physics is causing this. And yes you can not explain all that goes on with that barrel harmonics here but with the basics it's easy to understand and that is all that most people will need to know.
Shep

 

[thwatson2]

Barrels come in all kinds of thickness. Most bull barrels are for heat dissipation and not accuracies. You can get fluted barrels, bull barrels and sporter barrels. Depending on twist rate, material, thickness, and the shooter, barrels make or break a great shooter. Most barrels out shoot the the shooter. If you plan to shoot a lot in short periods (bull barrel), shoot an elk at 200 yards in a days hunt (sporter). Whatever Thick barrels don't mean more accurate or better. I own 5 browning boss rifles(awesome shooters). I can make any factory load very accurate with the boss. Or I can handload the right powder per bullet to shoot well in most barrels. Barrels vibrate, we can overcome this by adding (boss), cryogenic treat, handload to compensate vibration, etc. My thoughts are, take a gun with a barrel and figure what it likes, what velocity, what bullet weight, what powder, what bullet brand, what primer. This is why I continue to partake in this forum. Learn, shoot, and just develop. You can't outshoot a good barrel!