Barrel fluting: yea or nay

I believe proper fluting won't affect accuracy at all, but of course there always is the possibility of the fluting NOT being properly done which can cause stresses in the barrel that wouldn't be there without it. Fluting is solely a weight reduction move so if you can carry the full barrel it's better off without it.

Properly fluting a barrel does three things:

1) Decreases weight.
2) Increases surface area.
3) Increases barrel stiffness.

Personally I like fluting when done by a competent party as I get a lighter barrel that shows less POI change as the strings are fired.

Sorry....I was hoping this wouldn't devolve into a fluting discussion, but #3 is just not correct. Fluting does NOT make the barrel stiffer....you're taking away material which will always decrease the material stiffness. The fluted barrel WILL be stiffer than an equal weight one due to its' increased diameter but comparing equal diameters the non-fluted will always be heavier and stronger.

I think that fluting does not increase stiffness.

It results in a barrel that is stiffer than one of the same weight, but not diameter.

Removing material does not make it stiffer, it makes it lighter than one of the same original diameter.





Darn it, sniped by Recoil Rob

Its the flutes on the inside of the barrel that count.

but it looks cool

Yes, I was not precise when I mentioned stiffness. I should have written:

A fluted barrel will be stiffer than an unfluted barrel of the same weight. If the unfluted barrel weighs the same as the fluted barrel, by definition the unfluted barrel must be smaller in diameter.

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Cooling and/or rigidity factors not withstanding, it's kitschier fer sure.

Fluting is a controversial subject precisely because there is no database of testing to show anything one way or another.

Until serious back to back testing with documented results conducted in a scientific manner with a large sampling is involved. a lot of us are going to point out that fluting is a largely cosmetic exercise and it's questionable whether you get anything positive out of it.

Rifling, contour, muzzle crown, leade, and barrel length that minimizes harmonics in muzzle movement are all more important and have to be addressed first.

If fluting was really a known improver we should be able to point to a test of dozens of barrels which were documented for their accuracy, then fluted, then shot to prove there was improvement.

Links? Not hearsay - links or references to independent testing. Until then for many it's still a case of gun show marketing for the well heeled. Plenty of that introduced every year at SHOT.

It depends on your goals. I have one hunting rifle with a fluted barrel and like it for my uses.

A heavier un-fluted barrel will be the stiffest and in theory be the most accurate.

A pencil thin Mt Rifle or Featherweight type barrel will be the lightest, but you usually give up some accuracy especially if multiple shots are fired in a short time.

Fluting won't make a barrel stiffer, but it will reduce weight without giving up stiffness or accuracy. The greater surface area should aid in cooling, but I consider this secondary and not that big of a deal.

I often hunt in some steep rugged terrain. I've used some of the thin barreled rifles in the past. They are a joy to carry and accuracy was acceptable. But the fluted rifle I've been using lately is only a bit heavier, certainly lighter than a standard barrel. But I don't feel I'm giving up any accuracy at all compared to standard weight barrels.

Is Remington still making the triangle barrels?
I heard they shot very well, serendipitous or not.
........and what about spiral flutes

My old Ruger Mk II "light sporter" in .223 is a half-MOA shooter for five shots. Works well on prairie dogs to 300 yards.

I guess that's why I've never given thought to owning a fluted rifle.

Is there a lady or gentleman (or engineer) that would be so kind as to calculate the weight savings of fluting (showing their work)?

From WOA's site describing the fluting on the SDM barrel.

Inspired by the Army's SDM-R Squad Designated Marksman rifle, this 20" stainless steel AR15 barrel features 12 large flutes to reduce weight and aid in cooling. Nearly a full pound of weight is removed from the barrel and the surface area in the first 12" of barrel length, where the majority of heat is generated, is increased a whopping 81%. Barrel weight is just 2lb 9oz.

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https://www.whiteoakarmament.com/sh...designated-marksman-sdm-barrel-1-7-twist.html

Is Remington still making the triangle barrels?
I heard they shot very well, serendipitous or not.

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I had a VTR in 22-250. It shot very well. I ended up trading it for a CZ though and don't regret it. The porting or brake was obnoxiously loud.

Tirod said:

Until serious back to back testing with documented results conducted in a scientific manner with a large sampling is involved. a lot of us are going to point out that fluting is a largely cosmetic exercise and it's questionable whether you get anything positive out of it.

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Before I get started I have no axe to grind re flutes. I've owned and still own rifles with fluted barrels and rifles without fluted barrels. In addition I have accurate rifles with both configurations. I "built" two very accurate F-Class rifles using fluted Krieger barrels and both were incredibly accurate. I currently have three AI rifles including an AW in .308 Win/6.5 Creedmoor, an AWM in .300 Win Mag and an AWM in .338 Lapua Mag. The magnums have fluted barrels the AW does not. All three are IDENTICAL to the rifles issued to British troops and myriad other armed forces around the world. I do not think for one second that AI fluted the barrels for cosmetic purposes. Anyone who's owned or shot an AI will know how accurate they are and that they're built for serious use, not to be aesthetically pleasing. Flutes when done properly do increase barrel stiffness compared to a non-fluted barrel of the same weight. Do they help in heat transfer ... maybe, maybe not. Flutes done poorly can certainly add stress in a barrel and result in poor accuracy, particularly as the barrel heats up.

As the late great Gale McMillan (Mr No Barrel Breakin Needed) said, the main effect of barrel fluting is to move money from your pocket to the machinist's.

Tirod said:

Fluting is a controversial subject precisely because there is no database of testing to show anything one way or another.

Until serious back to back testing with documented results conducted in a scientific manner with a large sampling is involved. a lot of us are going to point out that fluting is a largely cosmetic exercise and it's questionable whether you get anything positive out of it.

Rifling, contour, muzzle crown, leade, and barrel length that minimizes harmonics in muzzle movement are all more important and have to be addressed first.

If fluting was really a known improver we should be able to point to a test of dozens of barrels which were documented for their accuracy, then fluted, then shot to prove there was improvement.

Links? Not hearsay - links or references to independent testing. Until then for many it's still a case of gun show marketing for the well heeled. Plenty of that introduced every year at SHOT.

Click to expand...

There is a load of engineering/strength of material data that shows a cantilever beam with a higher moment of inertia will be stiffer than a beam of similar length with a lower moment of inertia. There are also loads of data showing that thick walled tubes with longitudinal lightening cuts (flutes) are much stiffer than thick wall tubes without longitudinal lightening cuts of the same weight, due to the higher moment of inertia of the larger average diameter of the fluted tube.

There is also much scientific data that show the if you increase the surface area of a hot object, the rate of heat loss due to radiation goes up.

There is tons of scientific data showing the more mass an object has the more heat it can absorb for a given temperature.

Therefore, there is no question that a fluted barrel will be stiffer than an unfluted barrel of the same weight, and will reject heat faster. Unless you happen to live in a place where the laws on nature and physics don't apply.

You can argue about whether or not stiffer, heavier barrels are more accurate than lighter more flexible ones, but you cannot argue that:

1) a fluted barrel will be stiffer than an unfluted barrel of the same weight.
2) a flutted barrel will have more surface area and therefore reject heat faster than unfluted barrel.
3) the heavier the barrel the more rounds it will take to reach any given temperature.

Jim Watson said:

As the late great Gale McMillan (Mr No Barrel Breakin Needed) said, the main effect of barrel fluting is to move money from your pocket to the machinist's.

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Gale McMillan supposedly made this post on another forum almost 20 years ago.

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Posted: 12-02-1999 10:53
In the 1970s a bunch of target shooters were in our barrel shop and the subject of fluted barrels came up and the point of the discussion was that
they wouldn't shoot well enough for target guns. That was the reason you never saw one on the line. After the discussion broke up I was talking
about it with my brother and we decided to make a couple of barrels and flute them at a point in the manufacture that we thought it should be done.
We made two and one was given to Harold Broughton of Big Springs TX and I put the other on my brothers gun. To make a long story short Harold won
the NBRSA Nationals and Pat won the IBS Nationals and set two worlds records. I will say that while these two barrels were outstanding barrels it
was in spite of being fluted and not because of it. After that everyone was fluting barrels and at any point from after they were made to before they
were drilled. For my own point of view you couldn't' run fast enough to give me one that some one else had fluted.
I once asked another barrel maker why he fluted barrels and he answered . $2.00 a minute! That was what he made in fluting them.

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So this whole "Gale McMillan is against fluting" is based on two barrels that he made, a comment made by another barrel maker and his comment that fluting is not necessary but is ok as long as he's the one doing it.

Interestingly and perhaps ironically, the McMillan TAC-50 A1-R2 issued to the Navy SEALs as the Mk 15 has a fluted barrel.

stokey in post 14.

You can take the radius of your bbl, square it, then multiply by pi, (3.14159) then multiply by length. That will give you the volume.
Multiply the volume by the weight of whatever material your barrel is comprised of (maybe in cubic inches, for instance).

Next, measure the depth, width, and length of all of your flutes.
Multiply the depth times the width times the length times the number of your flutes and subtract that volume from your first number.


Good grief, I have one barrel that's fluted and haven't yet been convinced flutes are worth having.

Is there a lady or gentleman (or engineer) that would be so kind as to calculate the weight savings of fluting (showing their work)?

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1. Steel or stainless steel has a density of 0.289 lb/in^3
2. Assume six flutes 20" long with a diameter of 1/4"
3. Assume that the ball end mill is set up to cut half the cross sectional area of the ball

Cross sectional area of ball end mill divided by 2 X density of stainless steel X length of flute x number of flutes.

(PI/8*0.25in^2)*(0.289lb/in^3)*20in*6

= 0.85lb

I think part of the misunderstanding about fluting is that when you add them....you remove weight. Period. Edit: Unless it's done by a hammer forging process where no material is actually removed and just the effective diameter is increased in which case it WOULD make it stiffer by way of that increased diameter...but the weight would remain the same.

You cannot remove something from a tube and make it stronger by doing so...which then brings in the comparative modifier of 'equal weight' that must be mentioned when talking barrels and fluting or confusion will be had for some people.

One way to think about it that I have used when trying to explain this particular thing: If fluting the barrel makes it stronger, then the deeper the flutes the stronger it will become? If not...why? Then the kicker: if removing some material from the barrel makes it stronger, then a barrel with all the material removed must be the strongest of all! Thankfully this often turns on the 'light of understanding' or the people just give up the argument and go find someone who will agree with them.

RecoilRob said:

I think part of the misunderstanding about fluting is that when you add them....you remove weight. Period. Edit: Unless it's done by a hammer forging process where no material is actually removed and just the effective diameter is increased in which case it WOULD make it stiffer by way of that increased diameter...but the weight would remain the same.

You cannot remove something from a tube and make it stronger by doing so...which then brings in the comparative modifier of 'equal weight' that must be mentioned when talking barrels and fluting or confusion will be had for some people.

One way to think about it that I have used when trying to explain this particular thing: If fluting the barrel makes it stronger, then the deeper the flutes the stronger it will become? If not...why? Then the kicker: if removing some material from the barrel makes it stronger, then a barrel with all the material removed must be the strongest of all! Thankfully this often turns on the 'light of understanding' or the people just give up the argument and go find someone who will agree with them.

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Flutes are not made with the hammer forging process. Hammer forging produces round profiles. If a barrel is advertised as fluted and hammer forged, a round blank is forged and the flutes are cut in that blank.