Mitigating Barrel Whip and Harmonics

[Mikecr]

That brake-born whipping is occurring after the bullet is released though. Right?

 

[kduffy]

Find the area of the barrel exterior. Find the area of a flute, (you need to know the diameter of the ball endmill used). Subtract the width of the flute area (remember you can only measure the chord length) from the barrel exterior area. Add the new area created by the radius of the endmill, at depth of flute, plus the area of any flute deeper than the radius of the endmill. When you are done, your new area is some percentage greater than the orginal area. This is a rough outline, you will need to pull out a geometry book to find all the arc lengths and really get accurate with the calculation.

It may be best and easiest to use a computer drafting program to "make" a barrel and then let the computer calculate the areas.

There may be some benefits of a shorter distance to the bore and "broken" surface to allow for more heat transfer. My recollection is that tube wall thickness makes more difference than surface area in heat transfer, but it has been a few years since I studied that. I believe these may total more than the minimal increase in surface area. When you work through all the math, the the percentages of gain I expect to be in the single digits.

My impression is that with fluting, you simply get the rigidity benefits of a larger barrel diameter due to the greater moment of inertia (squared factor)(just like an I beam gets much stiffer as it gets taller), with the benefit of the lighter weight of a slimmer profile. There may be some benefit to reduced mass, (and the spiral fluting could make the rotational acceleration of the bullet offset some of the energy). All of these will have effects on the harmonics just like tuning a stringed instrument. A change of 15% or more from a harmonic is best, but you take what you can get.

The bullet simply does not outrun the speed of the vibration in the steel. This leads us back to simply timing the bullet exit to the barrel harmonics with consistency at the most favorable node.

 

[nicholasjohn]

Has anyone done any vibration analysis studies? A natural frequency test could allow length to be optimized or dampening provided in the proper location without firing a shot. Many modern cell phones have an accelerometer in them that could be used to find a minimized vibration node to preset the adjustment of a dampener.

There used to be an adjustable barrel support that inlet into the forearm stock and allowed varying pressure as well. I have not seen these advertised in many years. It would eliminate the unsightly rubber donut and perform the same function. Does anyone have any experience with those?

I used one of those devices that was inletted into the barrel channel of the forend. It didn't work worth a darn, but the idea sure seemed like it should have. I have had much better results using shims made of a number of different materials for the same purpose - and it's a whole lot cheaper. Credit card shim worked OK; beer can shims worked better.

I think that the inletted device may have worked better if I had taken more time to figure out its tricks, but I didn't feel like investing a whole week at the range to sort it out when I could just default to a simple trick and get the job done in no time flat. With anything that puts upward pressure on the barrel, the stiffness of the stock's forend is the limiting factor. Some of the old injection molded synthetic stocks are so flexible that nothing helps, and whatever you get when you free-float the barrel ( by putting your beer can shim under the barrel shank ) is as good as you're going to make it shoot. With other stock materials, you may or may not get good results putting the shim up near the front of the barrel channel. You just have to try it and see what works. I would recommend starting out by putting the shim in the back, and if that doesn't bear any fruit for you, move it to the front. If one shim doesn't help, try two.

One thing that will take a variable out of the equation is a torque wrench. If you're going to take the gun out of the stock to fiddle with the shims, you need to know that the action screws are both torqued the same each time, or that will introduce another potential problem in to the equation. Given the choice, I would take the $$$$ you had thought about spending on the in-stock tuning device and spend it on the torque wrench instead. If you torque the screws to the specs that come with the wrench, you may find that you don't even need to try any shims …….

 

[25WSM]

There is absolutely no reason to mitigate barrel whip. It is necessary to get consistent barrel whip. Glass bedding and floating the barrel do this very good. Factory rifles put the pressure on the barrel at the forend because it helps them be more consistent mostly because they are not bedded. When you lock that barrel down into the pressure point it's kind of a 3rd point of contact over a longer distance to aid in the action staying more straight in the stock. The pressure point also changes your whip into a smaller window because it essentially makes your barrel half as long. And if you shoot factory ammo that is better. But barrel whip is what makes your tuning windows so it's not a bad thing for reloaders to have a bigger window. I guess I don't know what part of it you want to mitigate. Mitigate the inconsistency of it maybe touching the stock a little because if it is not free floated enough and touches that is bad. Really flexible stock forends are worse than skinny barrels for accuracy. So mitigating inconsistent barrel whip is great but barrel whip is nothing to be afraid of. It's a reloaders best friend.
Shep

 

[HARPERC]

..........Mitigate the inconsistency of it maybe touching the stock a little because if it is not free floated enough and touches that is bad.....Really flexible stock forends are worse than skinny barrels for accuracy. So mitigating inconsistent barrel whip is great but barrel whip is nothing to be afraid of.....

I think more clearance in some is necessary.

Totally agree with flexible forends.

 

[tacomHQ]

The formula to calculate for the area of a fluted system is shown.
We calculate the comparative aspects as compared to our barrels. While fluting is typically in the single to low double digits we are way into the triple digits concerning cooling area. Intertia calcs based on weight- again we are significantly superior to a standard flute.
I do not completely understand the thought of not mitigating or reducing barrel "whip" to an absolute minimum if possible. The greater the variation along the multitude of axis becomes an exercise in standard variables and non-standard. We were involved in the design of ultrasonic Welding/Drilling heads (our heads were some of the most extreme in the industry) for a decade or so, and I promise you small changes in shape, sizes, cuts, features can make huge unexpected changes. I learned more about what not to do than what to do. In these extreme cases reducing the variation to a minimum is a really good thing. Also a further note: vibration (whatever term you want to call it) varies with heat. In fact a 40deg rise in our tooling would go from optimum function to failure due to node migration. I do agree that you cannot eliminate "vibration" but I can reduce its amplitude, wavefront variation, intermixed wavefronts/frequencies, directions of the wave and amplitudes in all axis. We have split 60lb hardened D2 with bad frequencies. To me, barrels are just one more thing to tune.
If you want a specific answer to your fluting area questions - contact us.

 

[25WSM]

Spiral fluting gives you even more because each length of flute is longer. Yes barrel whip does move in more direction than up and down. And the more you decrease the variables of them all the more consistent your gun will shoot. But you cannot realistically eliminate it in a rifle. So you have to work with getting what you have behaving itself. If you had zero flex in your barrel it would be extremely hard to tune it. If you had a near perfect zero BC load it might work but as the temp nature changed the speed of the load it would be all vertical. You would have the very narrowest tune window possible. Not forgiving at all. However as your barrel whips up and down more your tune window will get better and better. Then if you can get your barrel to slow down its swing more at the top and bottom you will widen it more. By moving weight beyong the crown section of the barrel you get more whip that slows down longer at top and bottom of the swing swingwith less bore movement which is even better. It all real simple science. Made even easier to understand with the extensive charts and articles from Varmint Al. Its one of the reasons your rifle will tune better with a muzzle brake. They also shoot better because of the reduced recoil upsets the gun less while shooting. I'm laying in a hospital bed right now waiting for a disc removal on my l5-s1. Trying to help because it's a passion of mine for over the 30 yrs of building custom target and long range rifles. I don't have my computer with me to try and load some visuals but Varmint Al is one of the most knowledgeable people I know on the subject. As is Mike Ezzel. All the rifles we shoot have barrel whip right now and it's a very small amount seen by just a gap the size of a dollar bill can keep your barrel from touching the stock when firing. Unless it's a junk plastic stock where you better float it in multiple business cards of gap. This has been a very interestng thread and lots of info has come out of it. One reason I love this site so much is all the help offered up from some old timers and noobs alike. And like all free help its yours to do what you want with it. Gosh you just can't help loving this sport or the next nurse coming in to give me another shot of pain meds. Talk to you guys from my recovery side of all this. Happy holidays and hunting. This is the first opening day I have missed in 45 yrs. But hopefully I will have many more pain free ones in the future.
Shep

 

[HARPERC]

.......All the rifles we shoot have barrel whip right now and it's a very small amount seen by just a gap the size of a dollar bill can keep your barrel from touching the stock when firing. Unless it's a junk plastic stock where you better float it in multiple business cards of gap...,,,,

Truth!

Best wishes for your recovery. Pain doesn't help shooting form at all.

 

[25WSM]

Thanks Harp

 

[keithcandler]

Best wishes, and speedy recovery!

 

[HRM Johnny]

Spiral fluting gives you even more because each length of flute is longer. Yes barrel whip does move in more direction than up and down. And the more you decrease the variables of them all the more consistent your gun will shoot. But you cannot realistically eliminate it in a rifle. So you have to work with getting what you have behaving itself. If you had zero flex in your barrel it would be extremely hard to tune it. If you had a near perfect zero BC load it might work but as the temp nature changed the speed of the load it would be all vertical. You would have the very narrowest tune window possible. Not forgiving at all. However as your barrel whips up and down more your tune window will get better and better. Then if you can get your barrel to slow down its swing more at the top and bottom you will widen it more. By moving weight beyong the crown section of the barrel you get more whip that slows down longer at top and bottom of the swing swingwith less bore movement which is even better. It all real simple science. Made even easier to understand with the extensive charts and articles from Varmint Al. Its one of the reasons your rifle will tune better with a muzzle brake. They also shoot better because of the reduced recoil upsets the gun less while shooting. I'm laying in a hospital bed right now waiting for a disc removal on my l5-s1. Trying to help because it's a passion of mine for over the 30 yrs of building custom target and long range rifles. I don't have my computer with me to try and load some visuals but Varmint Al is one of the most knowledgeable people I know on the subject. As is Mike Ezzel. All the rifles we shoot have barrel whip right now and it's a very small amount seen by just a gap the size of a dollar bill can keep your barrel from touching the stock when firing. Unless it's a junk plastic stock where you better float it in multiple business cards of gap. This has been a very interestng thread and lots of info has come out of it. One reason I love this site so much is all the help offered up from some old timers and noobs alike. And like all free help its yours to do what you want with it. Gosh you just can't help loving this sport or the next nurse coming in to give me another shot of pain meds. Talk to you guys from my recovery side of all this. Happy holidays and hunting. This is the first opening day I have missed in 45 yrs. But hopefully I will have many more pain free ones in the future.
Shep

Get well soon! Thanks for all the help that you've given us.

 

[25WSM]

Thanks guys
I truly love helping to share the passion of our sport with others and really helping with tech help from what I've learned in the military and from Pittsburgh Gunsmith School and from all the fellows who kicked my but at matches over the yrs. Those guys always turn out to be your best friend. There are times on this site when I have to speak up because something is dangerous wrong. I will always say something in this case and not back down. But lots of stuff is very debatable. Debatable is a very healthy way of getting info from people that are passionate about their views also. There's normally no right or wrong way just different ways to skin the cat. I have learned much more from you guys on this sight than I have given. Was just on a thread about a fellow who didn't have a good result on game with a hornady 143eldx. He shot like 4 animals and lost one and the others ran farther than he liked. His in body damage assessment showed pretty good bullet performance but not DRT. But then everybody started telling of documented kills they and friends have had. I personally have killed 65 deer in my hunting efforts over 45 yrs. I got that much info pretty much from one thread in a few days. Seems almost everybody had excellent results. And people told of super man deer that don't know when to fall down. Vast info and quality info. Since I'm a gunsmith by trade I love seeing how others do things. The new top trends and everything about building rifles and reloading of precise ammo. I'm a mix of old school and new school and am a results driven learner. I can think of a new way to try something but until I prove it or disprove it it's just a thought. I'm very much a deciple of the Tannel method and Jim Bordin. Two of the most knowledgeable rifleman I know. So you can be old school and new school combined. Like me I learned old school from Dick Thacker in Pittsburgh and have combined countless new ways to do the same thing either better or faster or with more precision. Always learning. Sorry for the long post but it's late I'm in pain and can't sleep and just feel the passion here from everybody else. Besides there is no rest for the sick in the hospital.
I'll get to my point now. This sight is awesome and combines precision shooting and hunting and reloading and smithing and troubleshooting and so much more. If your new on here get engaged get your feet wet ask for help and give help. I'm sure everyone give the best answers they can from what I see. If something seems off ask up about it. Mistakes are made here too. You have to pick up on that too. And never feel bad if you try to clarify that yes they really meant 100% what they meant. It's easy to get a decimal point in wrong place or get dyslexia on the numbers for powder weights or have chrono that read a bit to high or low. I have been on threads that get heated up and threads that are like talking to mister Roger's. A Pittsburgh hero. So just stay connected to keeping this the best sight out there. And yes I'm on the other sites some but this is my favorite for sure. And for good reasons that I already said before. And keep putting those post up about your kids first buck or their first rifle. How many people forget the first gun you are given or first hunt and then first kill. Not me that's for sure. How many of you can open a jar of Hoppes and bring back 500 memories in one second. Yeah now I just rambling. But I'm allowed to do that here too. So buy a kid a bottle of Hoppes for Christmas and explain to him it's a memory jar and that no it won't get you rifle barrel clean.
Night folks. Shep

 

[nicholasjohn]

Spiral fluting gives you even more because each length of flute is longer. Yes barrel whip does move in more direction than up and down. And the more you decrease the variables of them all the more consistent your gun will shoot. But you cannot realistically eliminate it in a rifle. So you have to work with getting what you have behaving itself. If you had zero flex in your barrel it would be extremely hard to tune it. If you had a near perfect zero BC load it might work but as the temp nature changed the speed of the load it would be all vertical. You would have the very narrowest tune window possible. Not forgiving at all. However as your barrel whips up and down more your tune window will get better and better. Then if you can get your barrel to slow down its swing more at the top and bottom you will widen it more. By moving weight beyong the crown section of the barrel you get more whip that slows down longer at top and bottom of the swing swingwith less bore movement which is even better. It all real simple science. Made even easier to understand with the extensive charts and articles from Varmint Al. Its one of the reasons your rifle will tune better with a muzzle brake. They also shoot better because of the reduced recoil upsets the gun less while shooting. I'm laying in a hospital bed right now waiting for a disc removal on my l5-s1. Trying to help because it's a passion of mine for over the 30 yrs of building custom target and long range rifles. I don't have my computer with me to try and load some visuals but Varmint Al is one of the most knowledgeable people I know on the subject. As is Mike Ezzel. All the rifles we shoot have barrel whip right now and it's a very small amount seen by just a gap the size of a dollar bill can keep your barrel from touching the stock when firing. Unless it's a junk plastic stock where you better float it in multiple business cards of gap. This has been a very interestng thread and lots of info has come out of it. One reason I love this site so much is all the help offered up from some old timers and noobs alike. And like all free help its yours to do what you want with it. Gosh you just can't help loving this sport or the next nurse coming in to give me another shot of pain meds. Talk to you guys from my recovery side of all this. Happy holidays and hunting. This is the first opening day I have missed in 45 yrs. But hopefully I will have many more pain free ones in the future.
Shep

Shep,

Good luck with the surgery, and best wished for a speedy recovery. Next year about this time you'll be back out there chasing animals around, feeling like a champion again. Go easy on the nurses - they can make or break your hospital experience.


Nick

 

[tacomHQ]

Good day Shep,
I wish you a full and speedy recovery.
I know this thread is winding down, but I am still here in order to understand the challenges set before us. Of which, you appear to have a highly respected viewpoint.
I hope you are not saying we are offering a dangerous line of thought ie.. snake oil.
With that let's expand on that criteria.
Fluting: we can perform an in-depth analysis of fluting and its impact on strength and moments of inertia. The most basic argument: name a structure that uses a spiral shape to increase strength/rigidity. With that, I am curious what the exact outcome will be.
I think you are talking about dwell times at the ends of a cyclic event concerning the ease or forgiveness of a barrel.
I would like you to expand upon the thought that stiffer barrels are harder to tune: ours are absolutely stiffer and they are easily tuned across multiple bullet grain weights over wide bands of powder weights. You are approaching this thought from a specific point of view: please expand that point of view.
It is also interesting to note that 100% of the shooters who have gotten behind one of our barrels notes the unique recoil impulse. If you would visit our website you will see a video (third person) talking about that- free recoil shooting a .375CT..
I think there is a difference in problem-solving to obtain a temporary solution as in adding a card to a barrel in order to make it shoot. While it can certainly be appreciatingly gratifying it is not something easily forwarded to a timely, predictable, and cost-effective outcome. Versus a direct attempt to reduce the variables allowing a rapid to near-instant acceptable result.
Forgiving to me is how easily an acceptable result would be obtained. How many acceptable results can be obtained and over what operating ranges. While I truly appreciate the enjoyment of extended load development, passion, camaraderie, and time for self-thought - a near meditation, I also am driving for predictable empirical results.
I absolutely learn something from these threads- the passion thread spoke about "tuners" brings a new avenue to our work. More of a tickle of thought in the past versus a present earnest review requirement. Harmonic balancers: the most balanced rotation assembly will most likely improve its vibration aspects (unwanted or control of unwanted freq) with an elastomer-based balancer attached.
However ( I love car analogies): If I had to buy a new C8 Corvette on the caveat I had to tune it... how many buyers would there be?
With that: we are thinking about hosting an event this spring.
Each participant would bring two new - not shot- barrels. Large caliber and small caliber.
Mount them to their action at the site.
Each will have to shoot a wide range of grain weight bullets.
Choosing at least one bullet weight shoot at least a 4gr. powder spread.
Five shot groups, twenty (large caliber), thirty (plus) rounds small caliber, time-limited, for group size, group migration, SD.
Our goal is to raise the standards of what makes a premium barrel: ease of obtaining optimum accuracy, resistance to drift, extended barrel life, forgiveness across a wide range of loads and conditions, reduced felt recoil, reduced heat, and mirage.
I would appreciate any input you might have on the parameters of this test. You would be welcome to join us.
A big gamble for big results.
Please understand: this is an attempt to increase the knowledge of the sport, an exercise in documented results.
While you are sitting there counting the dots on the tiles on the ceiling in your room please take a moment and view some third party thoughts...