Fluted Barrels: Good or Bad?
- Thread starter Clevinger
- Start date
I've been a benchrest shooter for a long time and have never seen a fluted benchrest barrel. I agree with what jmr40 said about fluted barrels.
One thing that no-one has said yet is that a bead-blasted barrel has greater surface area, hence dissipates heat faster than the same outside-diameter fluted barrel.
I presently don't have any fluted barrels, but have put a deposit on a 2014, .223 Rem, 700 CDL, Stainless Fluted "Gun of the Year". I've been looking for a relatively light .223 for a walkabout rifle and this one caught my eye. It's unlikely to out-shoot my 9.2 lb Tikka 595, which is a true 1/4 moa rifle, but should be about two pounds lighter (if it ever comes in).
One thing that no-one has said yet is that a bead-blasted barrel has greater surface area, hence dissipates heat faster than the same outside-diameter fluted barrel.
I presently don't have any fluted barrels, but have put a deposit on a 2014, .223 Rem, 700 CDL, Stainless Fluted "Gun of the Year". I've been looking for a relatively light .223 for a walkabout rifle and this one caught my eye. It's unlikely to out-shoot my 9.2 lb Tikka 595, which is a true 1/4 moa rifle, but should be about two pounds lighter (if it ever comes in).
Sure Shot Mc Gee
New member
If Fluting was all that important to accuracy or weight. You would see the machining process done to these rifle barrels? (link) FWIW: Fluting a barrel is primarily a Poor Richards cosmetic machining. Sometimes beneficial sometimes not. Although the outward appearance of ones rifle is preferred by some verses their weapons overall accuracy and functioning. "if it looks cool. It is cool !!"__ yaw you bet-cha.
http://www.youtube.com/watch?v=6qatf5g7lzk
http://www.youtube.com/watch?v=6qatf5g7lzk
4runnerman
New member
I guess my question would be- In reality how much weight can you knock off by having this done?. I see some post's in here where someone will say ( this scope is 2 oz's lighter). Man I am old- But not to the point were 2 oz's is going to make a difference in the world. I mean my darn bullet is heavier than that. Now if we are talking 5 lb's difference or more-Go for it,If we are talking less than 2 or 3 lbs-whats the purpose. And to answer before I get asked- Yes I have carried my rifle all day long. Heavy barrel 223 and 308. My dang fanny pack with 300 or 400 rounds of 223 weights more than my rifle it seems. I think they look cool along with colored fluted Bolt's, but still have no interest in having it done
Jim Watson
New member
The late Gale McMillan, a favorite source on barrel break in for the gun boards, is seldom cited for his position on fluting. To wit, its main effect is to transfer money from your pocket to the machinist's.
Scubasimmons
New member
Less material does NOT mean it is less stiff. Changing the shape absolutely changes the structural properties. It doesn't matter if you believe me or not it is a fact. I will say I haven't actually done the math to determine the change in stiffness due to fluting, but another example would be blood grooves in old broad swords.
Regardless the potential positives out weight the negatives and it looks cool.
Regardless the potential positives out weight the negatives and it looks cool.
trigger643
New member
Back in 2004, Joel Avila took 3 barrels of the same length and caliber made by the same manufacturer.
Barrel #1 had an outside diameter of .840" and was non-fluted.
Barrel #2 had an outside diameter of .840" and was fluted to a depth of .70"
Barrel #3 had an outside diameter of .70" and was non-fluted.
Measuring the deflection at the muzzle (i.e. 'rigidity'), using 500#, the following results were observed:
#1 will deflect 4.4 inches.
#2 will deflect 7.5 inches.
#3 will deflect 9.5 inches.
And this goes to my point stated earlier. A non-fluted barrel of the same outside diameter as a fluted barrel will be stiffer, more rigid, than a fluted barrel of the same outside diameter. A non-fluted barrel of the same inside diameter will be less stiff, less rigid, because of a critical loss of structural material.
Mr. Avila goes on to explain the reason a fluted barrel cools faster than a non-fluted. It is not because of an increase in surface area. It is because there is less material between the source of the heat (bore), and the outside surface and less material for the heat to dissipate into.
Harmonics tests and muzzle deflection have also been conducted between fluted and non-fluted barrels with similar results.
Shall we flog this horse some more?
Barrel #1 had an outside diameter of .840" and was non-fluted.
Barrel #2 had an outside diameter of .840" and was fluted to a depth of .70"
Barrel #3 had an outside diameter of .70" and was non-fluted.
Measuring the deflection at the muzzle (i.e. 'rigidity'), using 500#, the following results were observed:
#1 will deflect 4.4 inches.
#2 will deflect 7.5 inches.
#3 will deflect 9.5 inches.
And this goes to my point stated earlier. A non-fluted barrel of the same outside diameter as a fluted barrel will be stiffer, more rigid, than a fluted barrel of the same outside diameter. A non-fluted barrel of the same inside diameter will be less stiff, less rigid, because of a critical loss of structural material.
Mr. Avila goes on to explain the reason a fluted barrel cools faster than a non-fluted. It is not because of an increase in surface area. It is because there is less material between the source of the heat (bore), and the outside surface and less material for the heat to dissipate into.
Harmonics tests and muzzle deflection have also been conducted between fluted and non-fluted barrels with similar results.
Shall we flog this horse some more?
Facts: Round barrels can be boringly round; fluted barrels are really groovy, inside and out!
Otherwise, round barrels have a tendency to be more accurate; but how much? That depends on how accurate your game with that barrel requires. Deer and varmints don't really care. Benchrest targets are really fussy about how accurately they're shot.
Otherwise, round barrels have a tendency to be more accurate; but how much? That depends on how accurate your game with that barrel requires. Deer and varmints don't really care. Benchrest targets are really fussy about how accurately they're shot.
Brian Pfleuger
Moderator Emeritus
I've rarely if ever heard that fluting makes a barrel "more" accurate and weight?... on the rifle in your example? Seriously? I'm pretty sure weight isn't a consideration on that gun.
Other than on the Internet, I've never met a person who claimed any functional reason for a fluted barrel except weight reduction. I like fluted barrels because I literally *like* fluted barrels. It's cosmetic.
As far as weight reduction, you can argue with Pac-Nor. They have a barrel weight calculator. According to them, 6 20" flutes on a 24" #2 contour barrel reduces it's weight by about 12 ounces. That's not insignificant.
ndking1126
New member
Although that's a very interesting article written by an Engineer officer with an engineering degree, I was disappointed to see that he clearly states the test to be theoretical, and not an actual test. I have no reason to doubt his math, but I am not an engineer and would like to have seen actual test results.
Steel will not get stronger when you cut it to change it's shape. It still has the same tensile, compression and shear strength no matter it's shape. A barrel is not a beam so it's not necessary to remove weight to carry loads across a span. Increasing surface area through fluting a barrel changes heat transfer to air time, changes harmonics, and reduces weight. I have no idea if any of these are advantages over round shape.
But I will take a guess. The harmonic changes could be a negative change. You would need to study fundamentals of harmonic resonance and how it effects simple or complex shapes. My guess is that you introduce some frequencies that were not there in the round shape. So, is that good or bad?
But I will take a guess. The harmonic changes could be a negative change. You would need to study fundamentals of harmonic resonance and how it effects simple or complex shapes. My guess is that you introduce some frequencies that were not there in the round shape. So, is that good or bad?
reynolds357
New member
Diameter for diameter, they are definitely not as stiff as a non fluted barrels. I think they look neat. I had a fluted barrel on a 1k rilfe one time and found it to be inferior to its identical profile non-fluted twin.
Jim Watson
New member
Seems like that one would get kind of leaky.
I suspect he MEANT that it was fluted to an effective diameter of .70" at the bottom of the flutes, but that is not what he SAID.
I considered a fluting job that would have taken off 14 ounces.
But it was easier just to turn it down to smaller diameter. On an AR for 3 gun, I doubt the rigidity matters much.
I do not believe that it makes a difference. Between me and my dad, we have 7 AR-15's all with custom barrels. All mine fluted, and all his are not. There is no difference in accuracy. Barely any difference in weight either. The only reason I get them fluted, because I like the look.
RaySendero
New member
Fluted barrels
trigger, LOL - Don't want to flog the horse, but:
That's still not apples to apples. I understand that the fluted barrel on the left calculates to 27% less deflection than the smaller diameter barrel on the right. However, that smaller diameter barrel will also weigh less than that fluted barrel!!! I wish he had figured the deflection (and % difference) between a fluted barrel and a not quite so smaller diameter barrel of the same weight!
But if he had, I'm guessing he would come up with an even LOWER/smaller difference than 27%.
trigger643 wrote:
.....
Shall we flog this horse some more?
trigger, LOL - Don't want to flog the horse, but:
That's still not apples to apples. I understand that the fluted barrel on the left calculates to 27% less deflection than the smaller diameter barrel on the right. However, that smaller diameter barrel will also weigh less than that fluted barrel!!! I wish he had figured the deflection (and % difference) between a fluted barrel and a not quite so smaller diameter barrel of the same weight!
But if he had, I'm guessing he would come up with an even LOWER/smaller difference than 27%.
Sure Shot Mc Gee
New member
Just a last minuet fickle thought.
If building or having a rifle built and offered the choice of fluting or a higher up-graded bull barrel for the same cost. I wonder which would be chosen more often. After all the rifle would have a decent quality bull barrel to begin with. Bull barrel to up-graded bull barrel whats the difference. One can only hold a rifle so still for so long on target. So where do I see a gain in accuracy. I'm uncertain. Maybe fluting for cosmetic's and that 12 ozs in weight savings is more practical after all.
If building or having a rifle built and offered the choice of fluting or a higher up-graded bull barrel for the same cost. I wonder which would be chosen more often. After all the rifle would have a decent quality bull barrel to begin with. Bull barrel to up-graded bull barrel whats the difference. One can only hold a rifle so still for so long on target. So where do I see a gain in accuracy. I'm uncertain. Maybe fluting for cosmetic's and that 12 ozs in weight savings is more practical after all.
reynolds357
New member
The only way I am aware of to have a bench rest grade fluted barrel is to flute the barrel before the rifling is cut. Fluting a finished barrel distorts the bore. Not much, but enough to screw up a b.r. barrel.
603Country
New member
What Reynolds just mentioned is the one thing that I would really be concerned about when getting an existing barrel fluted.
The following link's information is technically correct:
http://www.snipercountry.com/articles/realbenefitsbarrelfluting.asp
It’s not theory at all. Those 4th order equations are used all the time by engineers calculating rigidity for all sorts of round shapes of different materials.
But it's hard for most folks to understand. So, I'll try (probably the humpteenth time) to explain it it simplest terms.
* First, a popular concept....
Fluting a barrel makes it stiffer.
If you really believe that, you must also believe a patio deck made with 2x6's fastened together standing on their narrow 2" thick side can be made stiffer by replacing every other one with a 2x4. This equates to the flutes at the top and bottom of a barrel.
And you'll also believe a 6x6 beam made with three 2x6's laid flat atop each other can be stiffened by replacing the middle one with a 2x4. This equates to the flutes on the sides of a barrel.
Therefore, you must also believe if you remove material from something, it will bend less. Right?
* Second, grade school physics....
A long round tube in the horizontal position has half its mass above its center and half below it. Fixed at one end and a weight hung on the other end makes it bend down at its free end. The material in its top half gets expanded by some amount depending on its ability to stretch. And the material in its bottom half gets shrunk by some amount by its ability to be compressed. Same thing happens if it's bent sideways but 90 degrees away; one side compresses and the other side expands. If you remove any material, there'll be less to resist expanding and compressing.
* Third, changing those 2" thick boards to smaller metal pie slices....
Imagine a 0.9 inch pie made of steel that’s 24 inches thick. First, cut that pie into 12 slices. Then cut .15 inch off the slice’s inner tips to make a 3/10ths inch hole in the middle of that 24 inch thick pie. Bond them back together. Now you’ve got something like a 30 caliber barrel 9/10ths inch in diameter and 24 inches long made with twelve pie-slice shaped “wedges” of steel that are 3/10ths inch thick (bore diameter to outside barrel outer diameter), a bit less than 1/4 inch thick at their widest point (barrel outside circumference) and a bit less than 1/6th inch wide at their thin tip (bore circumference). ‘Tis nothing more than taking those boards in the above example and wrapping them around some axis.
Remove .15 inch from every other slice’s thick end and these six slices will now be a bit less wide at their thickest part and not as long from their inside edge to their outside surface. And this equates to replacing every other one of those 2x6's with 2x4's.
If you take the material cut off of those sliced and put it atop the uncut ones, those longer slices will have more area away from the pie’s center. That’ll increase the material that resists compression or expansion making those slices stiffer. Then the pie (barrel?) will be back at its original weight but will resist bending with more material further away from center. Same thing would happen with the deck if 2x4's alternated with 2x8's. Deck weight would be the same as if all 2x6's were used but a lot stiffer with more material added atop the widest boards. A board 1 inch wide and 1 inch high isn’t nearly as stiff in the vertical axis as a 1 inch wide board that’s 2 inches high
* What happens when you flute a finished barrel?
The stress on the metal makes it move from the flute’s cutting blades going into the steel. The internal diameters under the flutes will change a tiny bit; enough to be measured with precision tools such as air gauges and deep hole micrometers.
Button rifled barrels; the diameters get a bit larger, hammer forged barrels a bit smaller and cut rifled barrels - little, if any change. Minimal stress is the result as the metal’s scraped off in microscopic thicknesses in cut rifled barrels.
Unless you shoot your stuff into no worse than 1/3 MOA at 100 yards, you may not notice any accuracy degradation from fluting a finished barrel. But if the most uniformity in bore and groove diameters is wanted, flute the barrel blank before it’s rifled. Then lap the bore to uniform dimensions.
* In conclusion......
Few match rifles have fluted barrels because they do nothing to improve accuracy nor prevent changes in point of impact as they heat up. Good and even average quality barrels will not change point of impact as they heat up. Even when fired several times a minute, if properly fit to the receiver, impact doesn’t change. But as most folks reporting point of impact change with barrel heating up are using commercial factory rifles whose receivers’ face isn’t squared up with the barrel tenon axis, the high point on the face puts as stress point on the barrel and shot impact strings in the axis that point is from bore center. Cheap barrels that aren’t properly stress relieved will walk shots when they heat up regardless of how they’re fit to the receiver.
As a fluted barrel is less rigid than before fluting, its resonant frequency will be a little bit lower. Its harmonic frequencies are even multiples of its resonant one; second harmonic twice the resonant frequency, third is three times, fourth is four times and so on. Most barrels’ resonant frequency is less than 100 Hz, most in the 50 to 70 Hz range. Whatever its frequencies are, they are exactly the same for every shot fired regardless of the load used. Heavier loads make the barrel wiggle and whip greater amounts than light ones, but the frequencies stay the same. And for each successive harmonic frequency a barrel has, the amount of wiggle and whip for a given load gets less and less.
http://www.snipercountry.com/articles/realbenefitsbarrelfluting.asp
It’s not theory at all. Those 4th order equations are used all the time by engineers calculating rigidity for all sorts of round shapes of different materials.
But it's hard for most folks to understand. So, I'll try (probably the humpteenth time) to explain it it simplest terms.
* First, a popular concept....
Fluting a barrel makes it stiffer.
If you really believe that, you must also believe a patio deck made with 2x6's fastened together standing on their narrow 2" thick side can be made stiffer by replacing every other one with a 2x4. This equates to the flutes at the top and bottom of a barrel.
And you'll also believe a 6x6 beam made with three 2x6's laid flat atop each other can be stiffened by replacing the middle one with a 2x4. This equates to the flutes on the sides of a barrel.
Therefore, you must also believe if you remove material from something, it will bend less. Right?
* Second, grade school physics....
A long round tube in the horizontal position has half its mass above its center and half below it. Fixed at one end and a weight hung on the other end makes it bend down at its free end. The material in its top half gets expanded by some amount depending on its ability to stretch. And the material in its bottom half gets shrunk by some amount by its ability to be compressed. Same thing happens if it's bent sideways but 90 degrees away; one side compresses and the other side expands. If you remove any material, there'll be less to resist expanding and compressing.
* Third, changing those 2" thick boards to smaller metal pie slices....
Imagine a 0.9 inch pie made of steel that’s 24 inches thick. First, cut that pie into 12 slices. Then cut .15 inch off the slice’s inner tips to make a 3/10ths inch hole in the middle of that 24 inch thick pie. Bond them back together. Now you’ve got something like a 30 caliber barrel 9/10ths inch in diameter and 24 inches long made with twelve pie-slice shaped “wedges” of steel that are 3/10ths inch thick (bore diameter to outside barrel outer diameter), a bit less than 1/4 inch thick at their widest point (barrel outside circumference) and a bit less than 1/6th inch wide at their thin tip (bore circumference). ‘Tis nothing more than taking those boards in the above example and wrapping them around some axis.
Remove .15 inch from every other slice’s thick end and these six slices will now be a bit less wide at their thickest part and not as long from their inside edge to their outside surface. And this equates to replacing every other one of those 2x6's with 2x4's.
If you take the material cut off of those sliced and put it atop the uncut ones, those longer slices will have more area away from the pie’s center. That’ll increase the material that resists compression or expansion making those slices stiffer. Then the pie (barrel?) will be back at its original weight but will resist bending with more material further away from center. Same thing would happen with the deck if 2x4's alternated with 2x8's. Deck weight would be the same as if all 2x6's were used but a lot stiffer with more material added atop the widest boards. A board 1 inch wide and 1 inch high isn’t nearly as stiff in the vertical axis as a 1 inch wide board that’s 2 inches high
* What happens when you flute a finished barrel?
The stress on the metal makes it move from the flute’s cutting blades going into the steel. The internal diameters under the flutes will change a tiny bit; enough to be measured with precision tools such as air gauges and deep hole micrometers.
Button rifled barrels; the diameters get a bit larger, hammer forged barrels a bit smaller and cut rifled barrels - little, if any change. Minimal stress is the result as the metal’s scraped off in microscopic thicknesses in cut rifled barrels.
Unless you shoot your stuff into no worse than 1/3 MOA at 100 yards, you may not notice any accuracy degradation from fluting a finished barrel. But if the most uniformity in bore and groove diameters is wanted, flute the barrel blank before it’s rifled. Then lap the bore to uniform dimensions.
* In conclusion......
Few match rifles have fluted barrels because they do nothing to improve accuracy nor prevent changes in point of impact as they heat up. Good and even average quality barrels will not change point of impact as they heat up. Even when fired several times a minute, if properly fit to the receiver, impact doesn’t change. But as most folks reporting point of impact change with barrel heating up are using commercial factory rifles whose receivers’ face isn’t squared up with the barrel tenon axis, the high point on the face puts as stress point on the barrel and shot impact strings in the axis that point is from bore center. Cheap barrels that aren’t properly stress relieved will walk shots when they heat up regardless of how they’re fit to the receiver.
As a fluted barrel is less rigid than before fluting, its resonant frequency will be a little bit lower. Its harmonic frequencies are even multiples of its resonant one; second harmonic twice the resonant frequency, third is three times, fourth is four times and so on. Most barrels’ resonant frequency is less than 100 Hz, most in the 50 to 70 Hz range. Whatever its frequencies are, they are exactly the same for every shot fired regardless of the load used. Heavier loads make the barrel wiggle and whip greater amounts than light ones, but the frequencies stay the same. And for each successive harmonic frequency a barrel has, the amount of wiggle and whip for a given load gets less and less.