To flute or not to

[Richard Coody]

To each his own.

I would do it for weight savings but from what i have.read there is really not that much weight savings there

aesthetically they do look nice

But for me accuracy is paramount. Don't want fluting or barrel threading to possibly mess up a good shooter. Why take chances

 

[dmoran]

I have only had one match barrel fluted, which is the barrel I have been shooting for the past 4 years on my LT-Gun (1000-BR). The only reason I fluted it was for the weight savings, so that I could play with some attachments to my rifle and still make weight. Any how here is it's story:
31" Bartlein 6mm/243 ... HV... 5R ... .237" bore ... 8-twist ... cut rifled
6 flutes, 22" long each, reduced the weight 1-lb
Chambered in 6Dasher
Last group shot before fluting was a 3.7" at 1000yd
First group shot after fluting was a 3.9" at 1000yd
Overall accuracy, as good as any of my better barrels, both before and after fluting.
Capable of sub .3-MOA at 1000yds and has shot several 5-shot groups in the 2's.

My own input and opinions to fluting: experienced no gain or loss in accuracy, there for would do it again. But personally I would never flute a pulled "button rifled" barrel unless it was fluted before it is rifled, do to added stress. But the fluting to a single point "cut rifled" barrel is a form of stress relief, which can be done before or after rifling, as I did with this barrel.
Donovan

 

[IdahoSharpshooter]

I reread the chapter. The test parameters are very loose, and the sample is still miniscule.

In terms of hard evidence, like something that would be admissable in a court of law; it would be thrown out.

Donovan has personal experience with a barrel. He tested the way I would, FCH, shoot, then flute and compare.

I think Bartlein makes as good a barrel as anyone out there. They offer fluting as an option. I do not think they would if there were a tendency to degrade performance.

In the end, until someone posts a meaningful test, it comes down to opinions/preferences.

 

[JRS]

I reread the chapter. The test parameters are very loose, and the sample is still miniscule.

In terms of hard evidence, like something that would be admissable in a court of law; it would be thrown out.

Donovan has personal experience with a barrel. He tested the way I would, FCH, shoot, then flute and compare.

I think Bartlein makes as good a barrel as anyone out there. They offer fluting as an option. I do not think they would if there were a tendency to degrade performance.

In the end, until someone posts a meaningful test, it comes down to opinions/preferences.

Skip Otto and John Adams could have offered actual results, however, and unfortunately, they are no longer with us

 

[IdahoSharpshooter]

My Pence cut rifled barrel was fluted by Skip many years ago. I do not believe he would have done them if he were not convinced they helped. He was unique, even in this crowd. Skip kept meticulous records in a series of notebooks out in his shop. Wonder what ever happened to them...?

 

[rifleman700]

I reread the chapter. The test parameters are very loose, and the sample is still miniscule.

In terms of hard evidence, like something that would be admissable in a court of law; it would be thrown out.

Donovan has personal experience with a barrel. He tested the way I would, FCH, shoot, then flute and compare.

I think Bartlein makes as good a barrel as anyone out there. They offer fluting as an option. I do not think they would if there were a tendency to degrade performance.

In the end, until someone posts a meaningful test, it comes down to opinions/preferences.

You say you question the testing done but you don't specify what part you don't agree with.

As I read it the barrels - meaning all including CF and SJBS barrels were first tested for deflection / stiffness both cold and then after warming up the barrels. Both tests for deflection showed the same thing when only comparing the fluted and non fluted barrels and that is with more material the barrel is stiffer and has less deflection. It does not imply anything other than that, fluted is not as stiff as non fluted.

The next test was POI change as barrel heats up. Now this showed a couple of interesting things. The two heavy palma non fluted barrels from different manufactures were almost identical in POI shift when the two fluted palma barrels from different manufactures had quite a difference in POI shift. It would have been useful to know at what stage of the manufacturing process were each of these fluted. I am assuming they were both fluted by Bartlein and Krieger respectfully. There is quite a few things that could have come into play here as far as why they were so far apart but its not worth going in to. In this case maybe a third sample may have helped. One thing was clearly evident was that the non fluted palma barrels had 16% less POI shift than fluted barrels when only comparing them to the best sample of the fluted barrel.

You say you liked dmoran's test and yes I agree that I to like it but this test is apple and oranges. His test only proves that the accuracy did not show but very little accuracy change from non fluted to fluted. Nobody has questioned which one is more accurate. The tests performed by CZ for BL was meant to replicate in a small way the string of fire sometimes seen in PRS comps. Testing in book showed long strings of fire. I doubt dmoran ran these types of 50 round strings.

What is very interesting about this chapter in the book is the statement made by Harold Vaughn that in his studies and testing of barrels he found that a heavy flexible barrel is best

 

[IdahoSharpshooter]

rifleman700,

Donovan has done the only scientifically valid test, even if it is only one barrel. It's not apples and oranges. It's reality. He chooses to compete with the fluted barrel instead of replacing it. That is more solid data than Litz's. Competition does not allow for mulligans; score the bullet holes, group or score and call the next relay to the line. We have an answer at the end of the match, every time.

Litz' book takes Vaughn as gospel, and works from there. Vaughn always comes back to the phrase "computer simulations". When Litz quotes him, he used the term Experimental Results. He also states in reference to Vaughn, "that Vaughn did not provide ANY context OR DATA in the book to help us understand what led him to say that. It's SWAG, scientific wild aZZ guess.
Litz would not, imho, release a new Hybrid design to Berger with this miniscule a test program. He's a genius, but in this case this is not scientific testing sufficient to draw any meaningful conclusion from. The testing was also done out of doors. I shot Black Powder Cartridge Rifle Silhouettes for several years. The first year at the Quigley, I noticed just about all of the top shooters were using an MVA Montana Magnum rear peep. It differs by offering 12 different sized apertures. The gentleman who won, told me he changed aperture diameter from three to six times in a six hour match. With 600+ shooters relaying on eight stages, it takes a day and a half to shoot the match. He was compensating for cloud cover.

Another Example: for decades Sierra published a single G1 BC for their bullets. And, since we did not know better, we believed it. As the science of bullet design progressed, they were basically forced to show at least three G1's based in velocity. With modern bullet designs, like Brian Litz has done, G1 is just about junk science. Bullet companies cling to it because nobody (consumers) shooting wants to take the time and considerable expense to debunk the numbers. That and the fact that too many shooters opt to buy bullets with the highest BC. We also believed the MV numbers the ammunition companies provided us on the box. The advent of personal chronographs killed that notion.

One of the neatest thing about Litz's books; he accurately assigns a G7 value to other companies bullets. We owe him a great "Thank You" for that alone.

Some years ago I had an engineer friend from the Picatinny Arsenal. Do you want to know how many thousands of rounds, utilizing over 100 barrels they tested before moving to the second stage of testing? Six months work, to move to Stage II.

This is all opinions, and we vote with our wallets. If a barrel company offered all of their competition grade barrels fluted standard, but charged the customers over a hundred dollars not to flute, and non-fluted sales out numbered the fluted ones, would that affect the numbers/scores on the line?

 

[LHSmith]

From Dan Lilja:

"We've been asked if machining flutes into a rifle barrel causes stress in the steel. The short answer is no, it does not. To the contrary, fluting can and will relieve stress if it is already present. The same is true of any outside machining work performed on a barrel".

And in doing so there is a good chance this stress relieving (as a result of fluting) will cause the bore dimensions to increase which is why fluting is risky on button rifled or hammer forged barrels because it might cause a degrade in the barrels accuracy potential.

 

[IdahoSharpshooter]

LH,

interesting scenario you propose. Could fluting a barrel blank actually cause a change dimensions internally?

I had the pleasure of visiting both John Buhmiller and PO Ackley about forty-four years ago at their shops. I watched them both "bend" barrels that were a bit "crooked". They used that term to denote barrels where the bore ran true from front to back, but were not centered in the exterior. Basically drilled a wee bit off center. IIRC, the technical term is "runout". They did not have the equipment barrel makers do these days. And, the did not want the additional expense of chucking the barrel up in the lathe again to turn it true on centers. Instead, they would rotate the barrel to make sure the runout was up at twelve-o'clock and mark it for the customer's gunsmith to install.

It is my considered opinion that that is the reason some barrel makers used to offer two or more grades of barrels.

I wish I had kept more comprehensive notes back then.

 

[LHSmith]

LH,

Could fluting a barrel blank actually cause a change dimensions internally?

Very small change. Same as turning down a barrel to a lighter contour if done incorrectly. The bore diameter will increase slightly as outside metal is removed. Won't change at the chamber end if OD is not touched, but as it tapers smaller towards the muzzle end you may end up with a reverse choke in the bore.

 

[IdahoSharpshooter]

that makes sense. Thank You!

 

[Ray in Houston]

I need a new barrel and I "wanted" flutes.... now my head hurts..............

 

[JRS]

I need a new barrel and I "wanted" flutes.... now my head hurts..............

Don't worry. The barrel makers who offer fluting as an option, stand behind their work with the same guarantee that is attached to their non-fluted barrels.

 

[rifleman700]

Very small change. Same as turning down a barrel to a lighter contour if done incorrectly. The bore diameter will increase slightly as outside metal is removed. Won't change at the chamber end if OD is not touched, but as it tapers smaller towards the muzzle end you may end up with a reverse choke in the bore.

This is an issue that carbon fiber barrel manufacturers have had to deal with - radial compression.

 

[IdahoSharpshooter]

Which brings us to another question: if a barrel blank is first turned very close to the desired exterior dimension; then drilled, reamed, polished, and THEN rifled, might it be more accurate?

 

[ImBIllT]

Bartlein Barrels:
"Fluting will remove steel from the barrel making the barrel lighter and henceforth help make the rifle lighter overall as well. It will give the barrel more surface area which can help it cool a little faster".

Krieger Barrels:
" Flutes aid in cooling a barrel by exposing more surface area to the outside air. Flutes can also increase the rigidity to weight ratio of the barrel, thereby reducing barrel vibration and whip over a barrel of the same weight un-fluted".

Lilja Barrels:
"There are two advantages to using a fluted barrel. Improved accuracy because of increased barrel stiffness. If we compare a fluted barrel to one that is not fluted, both weighing the same, the fluted barrel is stiffer. This is because the fluted barrel will be of a larger diameter than an un-fluted barrel of the same weight and length. Increasing the diameter of the barrel greatly increases its rigidity. Another advantage is the increased cooling rate of the barrel because of the greater amount of surface area exposed to the air".

So…. WoodchuckWhacker, if you have experience and knowledge that our barrel makers do not have, feel free to entertain us and share that knowledge.

Generally they are the ones doing the fluting. When material is removed from an object, any stress in the object will cause the object to deform, because material that was previously holding it in place is now gone. In a forged or button rifled barrel, if fluting is done as the final operation(without stress relieving), the bore will expand underneath the flutes, because the flutes do not follow the rifling, the bullet will be constantly hitting larger and smaller sections as it rotates. This increases fouling. If a buttoned or forged barrel is contoured after rifling, and without stress relieving, then the bore will expand wherever material was removed. Stress relieving can lead to some deformation on its own. Cutting operations are considered not to induce streams. If you start with a stress free bar, and drill a hole, the cut rifle it, you can pretty much do whatever you like regarding contouring and fluting. If you start with stress, any operations will lead to deformation. If you forge or button rifle the barrel, you will induce stress. So if you contour the bar, the drill and button rifle, the narrow end of the barrel will resist the cutting bit less, causing a slightly smaller bore and the button will encounter a more flexible barrel on the narrow end causing a slightly smaller groove. This is largely okay because your bore is getting smaller at the muzzle end. With cut rifling you can drill and rifle the bar before contouring, and then contouring won't impact the bore. Butting doesn't induce as much stress as forging, and barrel makers often stress relieve. The result is that a barrel from a barrel maker that comes fluted is likely to be as good as any barrel. A barrel should only be fluted by a smith if it was cut rifled. A button rifled barrel fluted(or contoured) by a smith is not likely going to have nearly the same degree of problems as a forged barrel fluted by a smith. My experience with fluted barrels from Remington is that they make good tomato stakes! If you're going to contour or flute a buttoned or forged barrel, I recommend leaving the last 4-6" larger than the preceding area, and leaving that portion in fluted..

 

[jdh47]

It is pretty much a consensus that there are no perfect barrels. Modern techniques and materials have progressed to the point that we can get great barrels most of the time but exceptional barrels only sometimes. Tony Boyer goes through lots of barrels before he accepts one for competition. At least that is what he says in his book.

Ed Shilen once said that if you want to flute a barrel it would be better if you used a cut rifled one. Their tests led him to believe that it would be a mistake to flute their button rifled barrels.

Some people like fluting and some don't. Some barrels behave good fluted and some don't. About the only constant is that all barrels are not perfect and fluting only adds another variable.

Results do indeed vary.

Joe

 

[rifleman700]

rifleman700,

Donovan has done the only scientifically valid test, even if it is only one barrel. It's not apples and oranges. It's reality. He chooses to compete with the fluted barrel instead of replacing it. That is more solid data than Litz's. Competition does not allow for mulligans; score the bullet holes, group or score and call the next relay to the line. We have an answer at the end of the match, every time.

Litz' book takes Vaughn as gospel, and works from there. Vaughn always comes back to the phrase "computer simulations". When Litz quotes him, he used the term Experimental Results. He also states in reference to Vaughn, "that Vaughn did not provide ANY context OR DATA in the book to help us understand what led him to say that. It's SWAG, scientific wild aZZ guess.
Litz would not, imho, release a new Hybrid design to Berger with this miniscule a test program. He's a genius, but in this case this is not scientific testing sufficient to draw any meaningful conclusion from. The testing was also done out of doors. I shot Black Powder Cartridge Rifle Silhouettes for several years. The first year at the Quigley, I noticed just about all of the top shooters were using an MVA Montana Magnum rear peep. It differs by offering 12 different sized apertures. The gentleman who won, told me he changed aperture diameter from three to six times in a six hour match. With 600+ shooters relaying on eight stages, it takes a day and a half to shoot the match. He was compensating for cloud cover.

Another Example: for decades Sierra published a single G1 BC for their bullets. And, since we did not know better, we believed it. As the science of bullet design progressed, they were basically forced to show at least three G1's based in velocity. With modern bullet designs, like Brian Litz has done, G1 is just about junk science. Bullet companies cling to it because nobody (consumers) shooting wants to take the time and considerable expense to debunk the numbers. That and the fact that too many shooters opt to buy bullets with the highest BC. We also believed the MV numbers the ammunition companies provided us on the box. The advent of personal chronographs killed that notion.

One of the neatest thing about Litz's books; he accurately assigns a G7 value to other companies bullets. We owe him a great "Thank You" for that alone.

Some years ago I had an engineer friend from the Picatinny Arsenal. Do you want to know how many thousands of rounds, utilizing over 100 barrels they tested before moving to the second stage of testing? Six months work, to move to Stage II.

This is all opinions, and we vote with our wallets. If a barrel company offered all of their competition grade barrels fluted standard, but charged the customers over a hundred dollars not to flute, and non-fluted sales out numbered the fluted ones, would that affect the numbers/scores on the line?

Once again apples and oranges. Litz's tests were on deflection and POI change as barrel heats, period. It does not mention accuracy. And it seems you throw in all of that other info to deflect - pun intended, from this point.

 

[ImBIllT]

I have only had one match barrel fluted, which is the barrel I have been shooting for the past 4 years on my LT-Gun (1000-BR). The only reason I fluted it was for the weight savings, so that I could play with some attachments to my rifle and still make weight. Any how here is it's story:
31" Bartlein 6mm/243 ... HV... 5R ... .237" bore ... 8-twist ... cut rifled
6 flutes, 22" long each, reduced the weight 1-lb
Chambered in 6Dasher
Last group shot before fluting was a 3.7" at 1000yd
First group shot after fluting was a 3.9" at 1000yd
Overall accuracy, as good as any of my better barrels, both before and after fluting.
Capable of sub .3-MOA at 1000yds and has shot several 5-shot groups in the 2's.

My own input and opinions to fluting: experienced no gain or loss in accuracy, there for would do it again. But personally I would never flute a pulled "button rifled" barrel unless it was fluted before it is rifled, do to added stress. But the fluting to a single point "cut rifled" barrel is a form of stress relief, which can be done before or after rifling, as I did with this barrel.
Donovan

It's a cut rifled barrel. Your experience cannot be transferred to button rifled barrels. I haven't tested it, but it is my opinion that button rifled barrels suffer fewer ill effects than forged barrels and thick barrels suffer fewer ill effects than thin barrels. A straight taper or HV taper button barrel might be fine to flute after rifling, while a light Palma might suffer. I really don't know with certainty, but I won't recommend any contouring or fluting for non-cut rifled barrels once they've left the manufacture.

 

[ImBIllT]

Which brings us to another question: if a barrel blank is first turned very close to the desired exterior dimension; then drilled, reamed, polished, and THEN rifled, might it be more accurate?

No. For the most perfect bore the barrel should be drilled while it is a cylinder, and if it is to be cut rifled it should be rifled while it is a straight taper, then it should be contoured. The metal is trying to escape the cutter. Once tapered, the thin section is better at escaping the cutter. The bore will be smaller on the smaller diameter section. If drilled and rifled first, then contoured, the metal trying to escape the cutter during drilling and rifling is the same throughout the length of the barrel and the metal trying to escape the cutter during contouring is on the outside. Cutting does not induce stress.

If the barrel is to be buttoned, then it should be contoured, then drilled and rifled. If drilled and rifled first, the rifling would expand where material was removed on the outside. If contoured first, the material in the thin section will escape the drill more effectively, and the button will meet less resistance and thus expand the barrel less. Both effects result in a tighter taper at the muzzle than at the breech. This is not as good as a cut barrel, but it is better than being tight at the breach and loose at the muzzle.