Barrel Fluting = POI Shift

[SavageStag]

I know this will probably turn heated, but I thought it was very interesting as I have never heard of this before.


This is from the 2013 Sniper Magazine. Article by Tom Beckstrand

“ ….. One design change that resulted from AI’s exhaustive accuracy testing and development for the PSR is the removal of flutes from the barrel. Engineers at AI decided to isolate the barrel flutes to see what impact they had on accuracy. The Engineers attached a laser to the rifle’s receiver, another to the barrel, and a third laser to the scope. All three dots were zeroed to the same point, then they started shooting the rifle. They discovered that, no matter which fluted barrel they used the dots would diverge as the barrel heated. The dots from the lasers mounted to the scope and receiver would stay in place, but the barrels laser would manifest a POI shift. The POI shift from the warming barrel greatly diminished when they used barrels without flutes. Engineers determined that the flutes never heated evenly causing the POI shift. I hope that the results of this test gain wide circulation through the Sniper and Long Range Shooting Communities to help eliminate some of the ignorance that surrounds the perceived advantages of barrel flutes. …..”

 

[jimmykm21]

I don't know how it could turn heated unless someone can post data proving the article wrong.
I have never read of another firearm manufacturer conducting a test like this.

 

[TheGonz]

Makes sense. It's called Thermal Expansion. I have sheets that I use at work with different engine blocks and the amount of growth in microns with a given temp. It's a pretty quantitative value. All someone has to do is measure it, anyone heard of a cold bore shot.... Here we go!!!!

 

[Edds]

Did they see any difference between cut rifled and button rifled barrels?

 

[Grump]

Sure, I'll heat it up for you.

Without quantification, it don't mean jack squat to me.

Guess what? You have detectable amounts of PCBs in your blood and bones!!!!!!!! Whether it's *enough* to shorten your life by more than a week, well that's another topic. Surely not at toxic levels unless you have some really unusual exposure levels going on.

Show me these two things, and if both are satisfied I might give a shit:

1. The divergence of the barrel's laser dot exceeded .2 mils from the scope's; and

2. The point of impact for the launched bullet during warm barrel conditions correlated to more than a .1 mil deviation from the scope's dot and/or the cold-bore impact.

Next, what temperature differentials are we talking? Again, QUANTIFY. If it takes more than five shots in a minute to satisfy #1 and #2 above, I will care a little. If it takes 10 shots before it starts showing up, then I might plot hot-barrel POI shift like some barrels have a CDB/subsequent shots shift.

Finally, how do the actual FIRING tests of fluted vs unfluted barrels correlate? Cutting warm-barrel shift in half from .4 mil fluted to .2 mil unfluted would be worth worrying about. Cutting it in half from .2 to .1 mils, and I'm not interested. Reducing it from .2 mils unfluted to ZERO mils unfluted and I'll start looking at the purpose of the rifle and would care for the most precise uses.

Alas, it would seem that we continue to be doomed to having our precision rifles be pigs.

 

[coWSMasher]

I had a winchester model 70 extreme weather ss in 300 wsm beautiful gun loved the thing, but it got sent off to pacnor to be rebarreled because I am not shiting you it had an honest 3 inch change in poi from shot 1 to shot 2 and 4 more inches from shot 2 to shot 3. if i let the barrel cool for 20 minutes between firings it would put ragged holes at 200 but once that barrel got hot it was all over the place. This barrel is an extreme example as it is a pencil thin barrel with deep flutes. one thing that was interesting was it had the same shift every time.

 

[Boltfluter]

I had a winchester model 70 extreme weather ss in 300 wsm beautiful gun loved the thing, but it got sent off to pacnor to be rebarreled because I am not shiting you it had an honest 3 inch change in poi from shot 1 to shot 2 and 4 more inches from shot 2 to shot 3. if i let the barrel cool for 20 minutes between firings it would put ragged holes at 200 but once that barrel got hot it was all over the place. This barrel is an extreme example as it is a pencil thin barrel with deep flutes. one thing that was interesting was it had the same shift every

time.

Most likely this extreme change had nothing to do with the fluting but the inherant stress in this particular barrel. Contrary to popular belief
fluting relieves stress and does not create it. This is machining 101.

Regards,
Paul

 

[SnakeDoctor27]

If it wad that big of an issue, and common you would think more would have already complained about it, especially here on the hide but I have not recently heard of any modern systems with this issue... I'm not disagreeing but I don't see it being that detrimental so im with Grump..

 

[coWSMasher]

I was simply giving my experience with the issue. I know that is the only gun I have ever had that issue with and it is the only gun I have ever had with a fluted barrel. but as i said the shift was consistent if i shot three rounds at my normal relaxed pace waited 20 minutes and shot three more at the same pace when i went down range I had 3 little two shot groups. but as i said that barrel was incredibly thin with a lot of material removed via flutes. As a result i came to the conclusion that the flutes weren't heating evenly and/or the flutes weren't perfectly aligned which caused week directions in the barrel. In any case i am not planning on owning another fluted barrel.

 

[SavageStag]

Yeah I figured we would have heard of this "problem" by now too.

 

[blcouch]

I'm not as much of a shooter as a lot of guys on here and I also don't believe everything the .mil does or uses is gold , but have fluted barrels been used on sniper weapons in U.S. service in any number? What about foreign .mil? Just curious as I don't recall any except for maybe the SDMR for Army and maybe a foreign rifle here and there, and curious as to why they wouldn't do so especially if there is a weight savings. On the numbers of weapons we are talking about it shouldn't really be cost prohibitive.

 

[AEROMechanic]

If it wad that big of an issue, and common you would think more would have already complained about it, especially here on the hide but I have not recently heard of any modern systems with this issue... I'm not disagreeing but I don't see it being that detrimental so im with Grump..

Couple this with the fact that AI still continues to sell fluted barrels on their AW/AX series. Youd think after discovering a problem like this they'd cease production of fluted barrels altogether.

 

[rrflyer]

Did there impact shift? That's all I care about.

Metal expand/contracts.

Believe the bullet

 

[Masked]

Knights Armament ran Gov't tests several years ago and proved beyond a doubt (This is in another thread, this was JUST discussed last week) that fluting DOES make a difference in accuracy...So fluting DOES effect accuracy...However, that being said, because of the fluting, you're POI will always change to about the same area so, first shot low, high, high, high-right ~ That pattern will likely never change.

http://www.snipershide.com/shooting...-rifles/182191-anyone-lighten-barrel-mws.html

A few years ago we (KAC) did a Thermal Study on barrels with some .gov support.

Fluted barrels will yaw through the heat cycle. Now on a bolt gun, my guess is your going to see a significant issue. However doing it in a gas gun is not a great idea.
Stress is imparted in fluting, and no matter how well you flute the barrel will have inconsistent stresses, add in heat and it will start to yaw in a specific direction.
That is part of the reason we 'dimple' out barrels as it was found that if dimpled correctly the stresses imparted are not linear, so it will not yaw.

Now if you knew what temp your fluted barrel was - you most likely could predict where the POI would be moving to, as the results seem to be very repeatable for given heat cycles in the same barrel.

Now, on a bolt action, the POI will change but, not as dramatically...But, it WILL change slightly, especially if you're firing rapidly.

* I just realized I should have proof read my comment prior.

I had meant on a bolt gun you probably would not see major issues due to the fact the rate of fire is so low compared to the gas guns.

It has to do with thermal dynamics and how the heat is dissipated through the inlets...We're not talking 1moa here, we're talking maybe 1/10th or so from 100 on a Semi so, maybe 1/20th or so on a bolt.

 

[turbo54]

Contrary to popular belief fluting relieves stress and does not create it. This is machining 101.

Not exactly.

You're right that cutting metal away relieves stress in the barrel - the stress that was in the metal that is removed via fluting.

However, the cutter itself induces new stresses to the metal left behind.

So, you're both removing and creating stress in the metal.

A note for those that don't understand "stress" in materials:

Essentially the grains of metal are preloaded against one another, like sardines bunched up in a can. If you remove a sardine, the ones all around it are able to relax a little because what they were preloaded against is now gone. However, if you forcefully/traumatically remove the sardine (machining), you'll be changing the preload of the surrounding sardines into their sardine-neighbors.

The "stres relieving" effect of fluting is NOT to be compared to the heat treatment process called "stress relief". The fluting causes a very local effect, whereas the heat treat stress releif causes ALL the grains of metal in the material to relax and lose their preload with their neigbors.

Hope this helps a little.

 

[captrichardson]

Curious if that "Sniper/Beckstrand quote" was copied from a topic that I had posted at another site?

After the lovely discussion that took place in the original post that I made, I figured that it was not worth posting anymore on, but since it has come up, hopefully someone will be open minded enough to consider it.

I agree with what IMHO are the key contexts posted above "Science, Testing, and Quantifiable Results".

As much as it is taken for granted, I am not real sure that the Precision Shooting Community has as much of that as they really believe that they do. IMHO, there are a lot of "accepted standards" that if really put through scientific scrutiny would prove to be a lot of myth and urban legend.

I believe that the work that AI has done is bringing some of that to light. Bottom line, they scientifically measured the performance of a number of barrels, and found that there was a quantifiable difference between the performance level of a fluted and non-fluted barrel.

So why is this the first time that we have heard of this? My guess would be because no one has gone to the levels that AI did in their testing. My guess would also be, this is not the first time that this has come to light, but what is the popular reality, versus what are the scientific facts?

Case in point, look at how most rifles are tested for accuracy. Someone fires a 3-5 shot group at a very controlled pace at 100 yards, and Viola you have a rifle performance measurement. How true of a measure is that really?

This would explain why we see info that commonly states, there is no difference between a fluted and non-fluted barrel. Take 2 barrels, the only difference being one is fluted and one is not, fire a 3-5 shot group at a very controlled pace at 100 yards, and you most likely will not see a difference. Why, the barrels are not going through any type of full thermal cycle where temperature changes could impact those results.

In the testing that AI did, they fired at a pace that produced full thermal cycles, and that was when they noted the issues.

How many shooters run their rifles hard enough to produce full thermal cycles, I would bet not a lot. I would bet the ones that do, per some of the posts above, fully understand what was brought out in the testing that AI did.

Pretty basic science to me, a barrel going through full thermal cycles is going to want to move, how much it will move will be impacted by things like thickness, uniformity, stress, etc.

Food for thought.
M Richardson

 

[Masked]

Curious if that "Sniper/Beckstrand quote" was copied from a topic that I had posted at another site?

After the lovely discussion that took place in the original post that I made, I figured that it was not worth posting anymore on, but since it has come up, hopefully someone will be open minded enough to consider it.

I agree with what IMHO are the key contexts posted above "Science, Testing, and Quantifiable Results".

As much as it is taken for granted, I am not real sure that the Precision Shooting Community has as much of that as they really believe that they do. IMHO, there are a lot of "accepted standards" that if really put through scientific scrutiny would prove to be a lot of myth and urban legend.

I believe that the work that AI has done is bringing some of that to light. Bottom line, they scientifically measured the performance of a number of barrels, and found that there was a quantifiable difference between the performance level of a fluted and non-fluted barrel.

So why is this the first time that we have heard of this? My guess would be because no one has gone to the levels that AI did in their testing. My guess would also be, this is not the first time that this has come to light, but what is the popular reality, versus what are the scientific facts?

Case in point, look at how most rifles are tested for accuracy. Someone fires a 3-5 shot group at a very controlled pace at 100 yards, and Viola you have a rifle performance measurement. How true of a measure is that really?

This would explain why we see info that commonly states, there is no difference between a fluted and non-fluted barrel. Take 2 barrels, the only difference being one is fluted and one is not, fire a 3-5 shot group at a very controlled pace at 100 yards, and you most likely will not see a difference. Why, the barrels are not going through any type of full thermal cycle where temperature changes could impact those results.

In the testing that AI did, they fired at a pace that produced full thermal cycles, and that was when they noted the issues.

How many shooters run their rifles hard enough to produce full thermal cycles, I would bet not a lot. I would bet the ones that do, per some of the posts above, fully understand what was brought out in the testing that AI did.

Pretty basic science to me, a barrel going through full thermal cycles is going to want to move, how much it will move will be impacted by things like thickness, uniformity, stress, etc.

Food for thought.
M Richardson

It's already been proven that fluting does effect POI after rapidly fired follow-ups however, because of how a barrel is made, the POI will "yaw" and stay almost the same so, it's predictable.

In a bolt action, you're not firing as rapidly but, the temperature difference remains. You can actually see this in the difference between a cold bore shot and a warmed barrel -- That's thermal dynamics.

In a semi-auto, it's going to make a difference, like I said before, maybe 1/10 at 100 and we're talking maybe 2-3 second intervals. On a bolt action, the effects will be a bit less but, they still exist...Thermal dynamics don't just go away because we will it too...But, we're talking 1/20 ish from 100 maybe...

The bottom line is yes, fluting effects accuracy because of heat dissipation but, it's a predictable shift, the same as cold bore -> warm bore, is...

 

[Graham]

qr = [2p Lk (Ts1- Ts2)] / [ln(r2/r1)]

qr = rate of heat transfer
L = length of barrel
K = thermal conductivity constant for steel
Ts1 = temperature inside bore
Ts2 = outside temperature
r2 = thickness of barrel from bore to surface
r1 = radius of caliber, in this case it's .154" (.308 / 2)

The higher the qr value, the faster the barrel cools.

 

[steelman303]

in response to coWSMaster's 1st post above,

oddly enough, my Win model 70, chambered in 270Wby mag... does the same thing... It's a great hunting rifle to make the first shot with, but after that, it's all over the place when the barrel heats up.
Kicks like a damn mule, but puts deer on the ground on the first shot.

 

[ZombieSlayer]

Now do the same test with a fluted barrel and a sporter profile barrel of the same weight. That's the real test. Doesn't take a genius to know more metal will be stiffer ie no flutes.

Without a test on fluted vs sporter all you can really take from it is a heavier barrel weight is better (used loosely). Do the test with a sporter and see if it's actually flutes that cause it or just the heavier weight and increased strength of a larger profile solid/unfluted barrel. That's what I'd be more interested in.

 

[walley2960]

Now do the same test with a fluted barrel and a sporter profile barrel of the same weight. That's the real test. Doesn't take a genius to know more metal will be stiffer ie no flutes.

Without a test on fluted vs sporter all you can really take from it is a heavier barrel weight is better (used loosely). Do the test with a sporter and see if it's actually flutes that cause it or just the heavier weight and increased strength of a larger profile solid/unfluted barrel. That's what I'd be more interested in.

This brings up a good point. I have been reading with interest as I have a fluted barrel coming soon(first for me right weight for project hunting gun). After reading the rest of the posts I am unsure whether the testers used barrels of the same weight or the same contour. I know that steel expands/contracts with temperature changes. The fact is no matter how tight tolerances are. No barrel can be perfectly concentric The gun drill does not make a perfectly straight hole. Barrels are indicated off the hole at both ends before contouring. Make for inconcistant thickness around the bore. Additionally even heating/cooling of the barrel does not take place throughout the string of fire. I stands to reason that all barrels will/could have issuses with thermal drift. It seems the only reasonable thing to do is test each barrel/rifle and see how it acts under all senerios likely encountered in the field. If you find that if is acceptable to you then use it. If not then replace it.
I hope mine works out. I not it should make a decent tomato stake.
FWIW
Wally

 

[Xshot]

I had a winchester model 70 extreme weather ss in 300 wsm beautiful gun loved the thing, but it got sent off to pacnor to be rebarreled because I am not shiting you it had an honest 3 inch change in poi from shot 1 to shot 2 and 4 more inches from shot 2 to shot 3. if i let the barrel cool for 20 minutes between firings it would put ragged holes at 200 but once that barrel got hot it was all over the place. This barrel is an extreme example as it is a pencil thin barrel with deep flutes. one thing that was interesting was it had the same shift every time.

In the early 80's I ordered a Remining KS mountain rifle from Remington's custom shop. It came with a 26" non-fluted pencil thin barrel. It was a nice lightweight package with the kevlar fiberglass stock. It was not a rifle that could be used to shoot groups. Cold bore shots were repeatable, but as the barrel heated up POI would shift up to 1 MOA. POI shift were predictable, but OAT played into predictability. Too much variability, so I sold it. Needless to say, I don't own any pencil (mountain) contour barrel.

Similar experience, but fluting played no role in POI shift.

 

[lash]

This brings up a good point. I have been reading with interest as I have a fluted barrel coming soon(first for me right weight for project hunting gun). After reading the rest of the posts I am unsure whether the testers used barrels of the same weight or the same contour. ...It seems the only reasonable thing to do is test each barrel/rifle and see how it acts under all senerios likely encountered in the field. If you find that if is acceptable to you then use it. If not then replace it.
I hope mine works out. I not it should make a decent tomato stake....Wally

If you ordered your fluted barrel for a hunting rifle, this whole discussion is likely moot, as the likely-hood that you will fire rapidly and often enough to create any issues is slim in this arena (barring of course a day long prairie dog shoot).

Further to the discussion regarding assumptions that may or may not have been made when the test was conducted, it seems to me that we could argue all day about what assumptions may or may not have been made when the testing was done, but since the article posted discusses none of the assumptions made nor the conditions of the test, it's just so much noise and speculation and nothing else.

Now, if someone were to post the test scope, assumptions, controls, conditions and the resulting data...well we'd have something to argue about now wouldn't we?

Perhaps it's fair to take this article at it's face value (which isn't much), since few here have argued that there is no difference at all between fluted and non-fluted barrels. Since the article doesn't quantify the difference in POI, as Grump correctly pointed out above, there's nothing much to argue about, since it very well could be a difference of only .1 mil that was noted.

Author Beckstrand misses the mark if he thinks that people in the precision shooting community will just jump on the bandwagon just because. When he says, "I hope that the results of this test gain wide circulation through the Sniper and Long Range Shooting Communities to help eliminate some of the ignorance that surrounds the perceived advantages of barrel flutes. …..”, he provides no test results that can be evaluated and therefore used to convince people of his point.

 

[Boomholzer]

^ Exactly lash. Throw in a recognized Manufacturer's name and the term "engineers" and suddenly it is "fact".

This is no different than the Rain Vs. POI threads. Get a "scientist" or someone who totally misapplies a simple KE equation to throw numbers around and suddenly there is "fact".

Neither argument is controlled or quantified.

 

[RUMrunner]

I've seen coWSMasher's rifle do this, and I also know that the guys at Shilen (whom I trust a lot) do not recommend fluting and will not flute.

 

[walley2960]

Lash agreed it should be a mute point for my purpose. I really started drifting.

 

[AEROMechanic]

I've seen coWSMasher's rifle do this, and I also know that the guys at Shilen (whom I trust a lot) do not recommend fluting and will not flute.

If the fluting is done incorrectly (i.e. If the flutes arent all the same depth, width or spaced evenly.) then your going to see a dramatic P.O.I. shift. There is no logical reason to not do flutes.

 

[coWSMasher]

I agree that the only way you are going to see a 1 directional point of impact shift is if the flutes aren't cut evenly spaced or even depth. That being said it is impossible for them to be perfectly cut. so by adding flutes you are adding more steps to mess things up.

 

[Lowlight]

The missing part of this story is:

Button vs Cut Rifle

That is the crux of the discussion, he did not qualify his data as AI has access to both, Border / Bartlein Cut Rifles and Lothar Walther Button. (I know Bartlein was not used) So if they used the Lothar, which is the high probability, then yes, fluting a button rifled barrel increases the chances of failure. There a lot of caveats when using a button rifled barrel, contour and fluting is part of that.

I can say, and I know this for a fact, during the PSR Trials, Accuracy was tested at 1000. The top two winners were Remington, and Accuracy International. Both were using Bartlein barrels, and Remington had the winning group with a Fluted Bartlein that Bartlein did the work on. AI used a different contour to save the weight. So fluting of a well made Cut Rifle barrel is not the issue. Fluting a button is....

What happens is, consistency in the steel directly affects the pull of the button. This can change from barrel to barrel based on the exact metal composition. Picture a pull with the rhythm of a heartbeat based on some relayed observations.

Most people will NOT flute a Button Rifled Barrel, now this may mistakenly translate over to ALL barrels, but the problems are not inherent to a Rifle Cut like they are with a Button Cut one.

AI more than likely used a Lothar, but the PSR Contract was won, including on the accuracy side by a Bartlein Cut Rifled that was Fluted.

 

[AEROMechanic]

How much more "accurate" was the Remington 700?

 

[Frank Green]

How much more "accurate" was the Remington 700?

It wasn't the Remington 700. The gun used by Remington was the MSR rifle.

Later, Frank
Bartlein Barrels

 

[Frank Green]

Lowlight, I'll try and get some of the information for you. But as a side note Border barrels makes button rifled barrels besides cut rifled ones as well.

Talk to you later.

Frank
Bartlein Barrels

 

[chainring]

I can't wait to get my SAC bartlein helical fluted barrel.

 

[scudzuki]

This is really bad news.
I just received a Brux M40 profile .260 barrel with flutes.

Now I'm going to have to use it for a tomato stake.

Joe

 

[Lowlight]

This is really bad news.
I just received a Brux M40 profile .260 barrel with flutes.

Now I'm going to have to use it for a tomato stake.

Joe

No, all they are saying is, consistency is an issue. You can very well have a stress free button cut barrel, but the consistency from barrel to barrel is what suffers because they can't predict the consistency (composition) of the barrel itself.

The metal is not all the same underneath. They are a composite of hard, harder, or not quite as hard section, this greatly effects a button cut. As the cutter is pulled through you are changing the speed on which is slices, this effects consistency. It has the potential to change the twist, and thus the accuracy of the finished product. You can go with a shallow flutes and limit the potential, and also the contour comes into play. With an M40 you have less chance of an issue, with a Remington Varmint you have a bit more chance of an issue.

People tend not to flute Button Cut Barrels because of the potential for trouble. Doesn't mean every single one is sour, just means the odds are greater, and when you are making that investment most people want to mitigate risk.

 

[Edds]

What is the depth of the flutes being talked about. I've never had a fluted barrel on a rifle. I currently have a new fluted Krieger 6.5 barrel. The flutes are only about .050" deep. It has an .800 muzzle and is 24 inches long. You could turn it down so the flutes were gone and still have about a #5 Sporter contour. I can't imagine the flutes having much effect on anything but the looks.

 

[Boltfluter]

Joe,

I have several fluted button rifled barrels of my own that are tack drivers. Much of it depends on the quality of the blank to begin with. Most likely you will be fine.

Regards,
Paul

 

[SavageStag]

I never thought about button vs cut rifled in this instance, although I have heard of problems fluting button rifled barrels. That would be good news to me because I'd like a fluted barrel sometime.

 

[Edds]

Joe,

I have several fluted button rifled barrels of my own that are tack drivers. Much of it depends on the quality of the blank to begin with. Most likely you will be fine.

Regards,
Paul

I thought Brux barrels were cut rifled.

 

[Frank Green]

First thing will say is that magazine and the articles seen in it has produced quite a commotion on this subject as well as another and we've received numerous questions on them by phone and email. Some of these articles also leave out a lot of information with nothing to back it up with when it comes to testing and how the data was collected and kept etc...

To answer a couple of things on the fluting as I made a couple of phone calls and emails. On the subject of the fluting and poi shift etc...that was the initial subject right now I'm pretty sure to go on a limb and say it was a LW barrel which are made by button rifling and was done in the U.K. from the information I received back. Those barrels where they were fluted the bores opened up on them and went sour from what I was told. So that tells me the barrels were not properly stress relieved and or the barrel blanks just retained alot of stress and when you fluted them the fluting operation relieved the stress and that causes the bores to go go sour. This is another verification to me that I'm against fluting a button rifled barrel. You have no way to measure or tell if a button rifled barrel has any residual amount of stress in the blank after rifling and stress relieving.

I will also say that AI did do some testing here in the States with our barrels and fluting geometry/styles. It's possible what they learned in this testing lead to more testing over in the U.K. but I'm not to sure which came first. Any way the testing they did here in the States was approx. 3 years ago with our barrels. What they were testing was the fluting profile that they spec'd along with the contour of the barrel and it was to aggressive. The flutes were around .150" deep at the muzzle and around .200" deep towards the breech end. The goal with the aggressive flutes on that particular contour was to save weight. What they found was that particular contour and fluted on .30cal. barrels they shot just fine but when they made that contour and flute spec. on a .338cal. they had consistency in accuracy and vertical stringing issues.

They then took the same contour barrel in .338 and shot it unfluted. It shot fine with no stringing etc...then they fluted the barrel but only went approx. .100" deep on the flutes it had no change in accuracy.

It seemed between the .30cal and the .338cal. barrels the .338's just reacted differently. Probably because of less material in the barrel due to the different bore size etc...

I know this will answer some questions but will raise others as well.

Later, Frank
Bartlein Barrels

So on that particular rifle and or barrel contour they changed the spec. on the contour to reduce the weight and just don't flute the barrels on that particular model and no issues.

 

[captrichardson]

Frank & Frank, thanks very much for the input!

I think the Beckstrand article is a good thing on the one hand because it will hopefully make people question the true value and performance capability of a fluted barrel. On the other hand, without the full details of the AI testing, then it really does just leave a lot open for speculation.

I am not sure if anyone has done any real extensive, quantitative, scientific "optimal barrel contour" testing?

Why is there an “AMU barrel contour”, because they did extensive testing on it or simply because they won matches with it?

What is really going to produce the best possible results under a full range of operational variables? What is optimal, length, weight, contour, wall thickness, steel hardness & consistency, machining processes, etc?

Obviously this has more of an impact for those who are operating on the extremes in terms of round count, rate of firing, target distance, POI consistency, etc. For an average shooter, the difference in performance level will probably never be recognized. Reality is, most rifles can outperform the operator. But in some cases, the operators are being limited by the rifles true capability, and that is where this could make a difference.

This also goes back to, what is the true measure of a rifles performance level? Is it a slow paced 3-5 shot group, or is it a nonstop 15-20 shot group? Is it measured at 100 yards or 1,000 yards? Is it measured at 70 degrees, or over a range from 0-100 degrees? Is it measured with a single optimized hand load, or a number of different types of ammo? Obviously the rifle had better be able to perform as circumstances dictate!

For the few shooters operating at the very top of the spectrum, it definitely matters. For the weekend hunter or range warrior, it is obviously way beyond anything they need to worry about.

Thanks again,
M Richardson

 

[tbeckstrand]

Hello Gentlemen,
I just saw this thread and thought I would post some additional information from the AI factory tour, the source for the information I used in the article. The statement made on the POI shift caused by fluting came from Ian, AI's engineering team leader in England. The test was run in the UK, so the barrels used in the test would have been LW. I did not think to ask how big the shift was or how deeply the flutes were cut into the barrel. Ian sketched out the experiment with the 3 lasers attached to the rifle and quickly summed up AI's findings. I included those findings in the article.
One theme that was consistent throughout the tour was the respect afforded Bartlein Barrels. Frank, your comments are much appreciated and very accurate. The quality control measures AI has in their factory in the UK are nothing short of spectacular. Those QC measures are for the LW barrels. (As and aside, AI can spot LW's production problems quicker than LW can.) When I asked what control measures were in place for the Bartlein barrels in the U.S, they were much less stringent due to the quality of barrels Bartlein provides. I left with the impression that Bartlein's quality goes unchallenged at AI, a reputation that Bartlein earned.
That's pretty much it. Given more time and more space to print, we could get much more granular with Sniper's content. We try to write about things that interest us and that appeal to a broad spectrum of readers. Follow-up and additional details are best handled in a forum like this one. This is a great place to learn and debate. Best, Tom

 

[Frank Green]

Thanks Tom!

Later, Frank
Bartlein Barrels

 

[scudzuki]

I thought Brux barrels were cut rifled.

Affirmative, Brux barrels are cut rifled; I was just trying to add some levity to the thread.

I have every confidence that the rifle will be a tack driver, and far more capable than the shooter.

I don't even grow tomatoes.

Joe

 

[cobra655]

I read that article and it made me question my choice of barrels for my custom build. I had already selected a Bartlein barrel but had wanted to go with a fluted barrel to save a little weight for the multi-purpose task it was to perform. As others have said with out specifics on how the tests were performed, it is hard to take the information and use it effectively. After reading the information in this thread I will still get a fluted barrel.

Again I am amazed at the amount of information I continue to see on this forum. Thanks!

 

[300sniper]

There is no logical reason to not do flutes.

cost vs. reward.

what's fluting add to a barrel cost? $150-$200 by the time it's fitted. if you shoot out a barrel a year, or more, that adds quite a bit to the expense. what are you TRUELY gaining for that expense? have you compared a barrel of the same weight/length to a fluted barrel to see how much accuracy is "lost" by NOT using a fluted barrel?

 

[DroidSniper]

Awesome thread. This reminds me of the debate over cross drilling brake rotors for more cooling in the auto racing world. As it turns out the main reason racing teams cross drill their rotors is to reduce unsprung weight and not for better cooling.

 

[leadbullet]

Wow you guys just blew my mind, usually when I miss, I launch another round and don't blame the barrel. Oh well live and learn but this one I am gonna forget about.
Cheers.

 

[LRShooter101]

Bump

 

[peterh]

In the early 80's I ordered a Remining KS mountain rifle from Remington's custom shop. It came with a 26" non-fluted pencil thin barrel. It was a nice lightweight package with the kevlar fiberglass stock. It was not a rifle that could be used to shoot groups. Cold bore shots were repeatable, but as the barrel heated up POI would shift up to 1 MOA. POI shift were predictable, but OAT played into predictability. Too much variability, so I sold it. Needless to say, I don't own any pencil (mountain) contour barrel.

Similar experience, but fluting played no role in POI shift.

Xshot, I also owned the same Remington KS custom shop maintain rifle, mine was in 270win. The best I was able to get that rifle to shoot was 1 moa with 3 very slow shots. Your right definitely not a gun for group shooting. The gun was such a disappointment, for a long time I thought I had gotten a lemon but now I see I wasn't the only one. thanks for your post....