Fluted barrels - true purpose?

[scootrd]

confused ,

First I read :
 A fluted barrel is mostly to maintain the stiffness of a heavy barrel, but without the weight.
 Along with this is the idea that the greater surface area will facilitate cooling.

yet then In another article I read:

Fluting does not make a barrel stiffer. However, the weight reduction allowed by fluting permits you to start with a heavier barrel contour and end up at the same weight as an un-fluted barrel of a smaller diameter contour.

fluting reduces total barrel mass. A metal object of lesser mass will heat up faster than one of greater mass. So, with fluting, your barrel may shed heat a bit faster, but it may also heat up more quickly in the first place.

Arn't the statements from each article conflicting ?

What are the true skinny , pro's and con's regarding fluting?
does a fluted barrel on a bolt action hunting rifle truly buy you anything?

[mdwest]

I dont know...
 
Ive always been told that fluting creates a more rigid bbl.. and that it sheds heat a whole lot faster..
 
Never thought about the heat build up thing.. but I would question that.. it seems to me that more surface area (created by the fluting) would allow heat to be shed AS IT BUILDS.. thereby negating the build up issue..
 
I do know this..
 
Shooting my wifes .243 with its fluted barrel, and my sons .243 without a fluted barrel side by side.. after putting about 20 rounds through each pretty quickly.. my wifes barrel is considerably cooler to the touch than my sons..
 
 

[roper]

Various reason fro fluting.  Some manufacturer like Krieger offer SS in a heavier contour than CM and you can order SS fluted and have same weight as CM.  Some offer light/heavy fluting plus # of flutes and that can help not only in weight but you can add inches to the barrel and you can spec the length of the flutes.

the rifles I have fluted barrel on they were done for weight reduction allowing me to spec heavier contour and little extra in barrel length.  I can't comment anything on barrel cooling etc since I'm not going to have another rifle build with same contour barrel unfluted just to check that out.

[mcwoodduck]

I work for a boiler company and if you take a bare tube and extrude finns out of it.  The same mass is in each tube.  The finned tube has 9 time the surface area and 9 times the heat transfer area of the bare tube.
From what I can understand of the fluted barrel taked the weight out, leaves the ridges to add strength, and about tripples the surface area.  Larger surface area accepts or disapates heat faster to equal temperature.  The ridges help to move heat awau from the core barrel.
Remember you 8th grade science that everything wants to be equal.  Osmotic pressure, salinity and heat.  The trying to even out heat creates the wind and creates currents.
As the powder creates heat that heat will mograte to colder areas as the heat rises it will create a vaccume that will suck in colder ambient air to cool the barrel, be it standard, heavy or fluted.
The original idea of he heavy barrel was the larger mass of the barrel ment it would take more heat to heat the barrel.  The larger diameter helped to diapate that heat.  The temp of the barrel is about hte same on the 5th round as a standard barrel is on the 2nd.

[kevinsmith5]

^the physics teacher gives that answer a +1 for scientific accuracy.

[scootrd]

ok , so if I understand correctly,  benchrest rifles that are used for competitive shooting may receive some added benefits from fluting due to weight restrictions and heat transfer due to many repetitive shots,  but if fluting does not increase barrel stiffness what true purpose or function could a fluted barrel on a bolt action deer rifle really offer? example Rem CDL SF with a 24" barrel.

Aesthetics ?

[Brithunter]

  but if fluting does not increase barrel stiffness what true purpose or function could a fluted barrel on a bolt action deer rifle really offer? example Rem CDL SF with a 24" barrel.

Aesthetics ?

It's cool and fashionable that's what .................................. oh and usually costs more so your pocket is lighter too.

[scootrd]

  but if fluting does not increase barrel stiffness what true purpose or function could a fluted barrel on a bolt action deer rifle really offer? example Rem CDL SF with a 24" barrel.

Aesthetics ?

It's cool and fashionable that's what .................................. oh and usually costs more so your pocket is lighter too.

Perhaps Remington thought it would help the rifles balance... I just don't see the benefit fluting a deer hunting rifle. Unless someone could point it out to me.

Perhaps a rifle used for varmints. But Deer really? just don't see it.

[bilmac]

The first answer you got was correct, the second was B.S. The guys here have explained the cooling advantage pretty well, as to stiffness you get the advantage of a larger diameter circle while limiting the weight. A larger pipe is stiffer than a smaller pipe. If you take two pipes that weighed the same but one was 1" dia and the other was 2" dia. the 2 incher would be far stiffer. Actually the radial surfaces may add to the stiffness too. You know how much stiffer a piece of corragated sheet steel is than just plain flat. If You rolled up a piece of corragated steel into a tube, then you would have about as stiff a piece as you could get for the weight.

[gunnut69]

You've received several correct answers but perhaps not cogently expressed. Fluting doesn't make a barrel stiffer, it allows most of the stiffness of a large diametyer barrel to remain while removing most of the weight of the large diameter barrel. It will reduce the amount of mass to absorb heat BUT we don't want to store the heat so the increase in surface area allows a much quicker radiation of that excess heat. So why flute a hunting barrel? It can increase the accuracy of a given barrel (would be really difficult to test) whilekeeping the weight of the rifle close to what a sporter might be. In an environment of high fire rates such as a p-dog town it might allow longer strings before cooling.. In a deer rifle I see precious little advantage as shots fired are relatively low and accuracy is much less than most rifles can produce already..

[scootrd]

Thanks Gunnut,
so if I understand your response fully , You agree the Rem CDL SF really serves no positive purpose with fluting their barrel except Aesthetics?

[bajabill]

I always go to Varmint Al for this subject.
 
http://www.varmintal.com/aflut.htm
 
Fluting a barrel will reduce its weight, reduce its stiffness also, but less than the weight reduction. Resulting in less barrel sag under its own cantilevered weight, and a higher natural frequency.
 
This I understand with the exception of why a higher natural frequency is (always??) better for accuracy.

[charles p]

Let's re-review the physics.  There is a giant difference between fins and flutes.  We are discussing the properties of shallow, rounded flutes as are commonly found in sporting rifles today.
Picture a cross cut showing the diameter of a barrell.  It is basically two circles (the outside barrell and the bore).  In the middle we have the steel.  Now divide the outside circumference into twelve equal arcs.  Every other arc will become a flute - ok.  Now invert  the odd arcs and you'll have six flutes.  Have you changed the arcs.  No.  You haven't even changes the surface area of the barrell, only the external shape of the barrell.  That addresses the frequent misconception that a fluted barrell has more area and sheds heat faster.  Remember, we are not comparing a finned barrell to a round barrell, but a fluted barrell to a round barrell and the area of our flutes is equal to the initial area of the twelve arcs (cylinder) we started with.  A sporting barrel may in fact have a different arc for its flutes, but the surface area change is extremely minimal and inconsequential as a heat sink.
Now lets address the strength issue.  Can any structure become stronger by removing a part of it?  Picture a solid steel round rod.  If you mill away the east-west sides, it is probably about as stiff in the north-south plane, but much less in the east west plane.  Keep on milling the rod to any number of sides you want.  As you remove material, you do not add strength.  I predict that any strength test measured across the bottom of two opposing flutes, will reveal a weaker barrell in that plane .  Maybe barrells should have an odd number of flutes to prevent this.  Still, they will not be stronger barrells by virtue of removing any steel.
When a flute is milled into a barrell's surface, weight is removed.  That is correct.  A flued barrel is lighter than the blank from which it is was milled, but also heavier than a barrell equaling the diameter of the bottom of the flutes.
Flutes sell barrell and guns, mostly because they appeal to buyers.  They look neat.  They are new.  We want them for their looks as well as any other percieved or disproven beneft.
 
 
 

[mcwoodduck]

When you talk about a cross section that may be the best way to describe what the flutes do.
The bar stock barrel will look like a washer.  Flutes in the barrel depending on how many
4 will look like a cross with a hole in it.
8 to 10 flutes will look like a bicycle sprocket.
Both will increase surface area and decrease weight.
I think the flutes are more to do with surface area and personal preferance than anything.  I see it as 4 times the area to rust.  but I do not shoot in hot places with hundreds of rounds a day like at a Dog town.

[scootrd]

Even if the flutes did allow the barrel to cool faster , doesn't the flutes also allow the barrel to heat up faster as well?.
I guess I'm not sold on the whole flute phenomenon as of late on bolt action deer rifles like the  Rem CDL SF
for example.  I just don't see the overall purpose.

[tacklebury]

Flutes act just like fins on a heatsink.  It transmits heat out to the edges where passing wind can help take it away.  If you are in a very calm environment, the flutes do very little.  More breeze, just like your car's radiator, will dissipate more heat energy. 

[kevinsmith5]

The increased surface area of the flutes will transfer heat into the air faster even without wind.

[charles p]

But the shallow radius flutes on our guns do not increase surface area.  They just move the same area around but there is little change in the area.  Think of a barrell as a combination of many equal arcs.  Flip every other one over.  Have you changed the total area?  Nope.  Have you strengthened it or weakened it?  Weakened it by removing material.

[drdougrx]

For a  hunting rifle...fluting...for me is aesthetic and serves no other purpose....my hunting battery is currently 50/50 fluted barrels.

[mcwoodduck]

For a  hunting rifle...fluting...for me is aesthetic and serves no other purpose....my hunting battery is currently 50/50 fluted barrels.

What half of the barrel is fluted?  top, bottom( that would make little sense as heat rises) front , back? 

[mcwoodduck]

But the shallow radius flutes on our guns do not increase surface area.  They just move the same area around but there is little change in the area.  Think of a barrell as a combination of many equal arcs.  Flip every other one over.  Have you changed the total area?  Nope.  Have you strengthened it or weakened it?  Weakened it by removing material.

Any groove increases surface area.  Even a small one.
If you cut an 1/8 inch trench into the barrel.  You have increased the surface area by 3 of what you removed.  The 1/8 you removed on the outside is not the floor of the trench and the two walls are both 1/8"  for a total of 3/8"
You may have not weakend it by removing metal.
Here is where therory and practice in metalergy I get lost.
The grooves allow heat to diapate faster and allows the metel to have less flex as it stay the same temperature longer and you do not get stress buy heating and cooling.  If you take a coat hanger and bend it, over and over in one spot it will break.  If you feel it at the break right after it is warm.  The heat and stress is what weakens the metal.  When I was going through this part of the high pressuresteam and pump sections I was kind of lost as to how a Super hot boiler did not distort and it was because of heat transfer and constant temperature being the answer.  If you super heat a boiler every day (High temp steam) and allow it to cool either over night or a few times during the day in an industrial process you will save energy but wear out the boiler dure to heat stress. 
 

[SHOOTALL]

 All that said I bet many buyers don't consider anything but "it looks cool "
 
 If strength was the goal then it would appear a octagonal bbl would be good as no mass was loss and 8 corners were made to add strength . For weight reduction fluting makes sense , cooling maybe , but air flow helps cool and depending on the orientation of the hot bbl air flow could be less across the bbl if flutes disrupt it .
 
The Flutes do look cool but so does an Oct bbl. When I shoot alot a damp cool cloth cools the bbl and action as well as anything. And no it dosen't hurt the gun.

[Silvertp]

The value of fluting that I most appreciate is the weight loss.  Weight reduction makes a rifle balance differently.  Maybe not a bunch, but can improve the balance and handling.  More important for some types of hunting that requires quick rifle handling.  Subjective, yes, but I think most would agree that some rifles balance better than others and if a little diet off the front of your rifle would make it feel quicker count it as a benefit.

Weight reduction also cuts down on total weight that a hunter must pack.  No big deal if you are walking 1/4 mile into a tree stand.  But if you are back-pack hunting for Dall sheep in the Chugach Range every ounce matters.  Ive seen guys cut the handle off their tooth brush and whack their stock off behind the grip just to reduce weight.

Silvertp

[roper]

I think there is only 3 posters that have fluted barrels and we stated why we like them.

[charles p]

I have a few fluted barrels also.
Consider this.  Picture a toilet paper tube.  Its area is fixed.  You can make it oval, flat, square, or whatever, but unless you add more cardbard to it, you are not going to increase its surface area.  Now crease it up and down its longest axis where you visualize those 1/8 inch flutes.  Make as many creases as you like.  Each time you make a crease, you change the tube's shape but not its area.  You will have to stretch the tube to increase its area or add more cardboard.
Agree or not?
 

[charles p]

I have a few fluted barrels also.
Consider this.  Picture a toilet paper tube.  Its area is fixed.  You can make it oval, flat, square, or whatever, but unless you add more cardbard to it, you are not going to increase its surface area.  Now crease it up and down its longest axis where you visualize those 1/8 inch flutes.  Make as many creases as you like.  Each time you make a crease, you change the tube's shape but not its area.  You will have to stretch the tube to increase its area or add more cardboard.
Another test you can do.  Remove your belt and rebuckle it.  Lets say it is now 36" in circumferance and 1" wide.  Compute the area.  Now rearrange the shape of that belt into a fluted circle.  Did you increase the surface area of the belt loop.  Nope.
Agree or not?

[Keith L]

When you put the creases in the tube or reshape the belt you make the circumference of the circle smaller to retain the same surface area.  With a steel tube like a barrel the circumference stays the same so the surface area increases.

[SHOOTALL]

A thinner bbl would reduce weight   

[drdougrx]

Mc.....top or bottom, front or back....literal translations.....you must be tak'n lessons from my wife!    
 
I still say fluting is a fad for most gun companies.  It makes the gun look cool and attractive with relatively little to be gained in weight reduction or barrel cooling for HUNTING rifles.
 
I have a 243 rebarreled by ER Shaw.  My choices were an ultra lite barrel or a magnum sporter taper.  Why they don't offer a standard sporter taper is beyond me.  So, I chose the MST rather than the ultra lite to increase barrel stiffness (bad choice in retrospect...so live and learn).  I asked if fluting would reduce the weight of the barrel...they said that weight reduction would be negligible but it would aid cooling after shooting several shots in rapid fire....y'know like a couple magazines one after another.  Not much chance at all that I'd do this, so I had it done anyway cause it looked cool.

[charles p]

Try this image.  Picture the rim along the dial of a clock.  There is an arc on the rim between the number one and the number two.  Lets call that arc a positive arc.  Now go to the arc between two and three.  Invert the arc.  Do not change its radius at all, just turn it over. Let's call that "upside down arc" a negative arc.  Do that all around the clock.  Invert every other arc. 
Have you increased the exposed area along the rim of the clock dial?  No.  Have you decreased the greatest diameter of the rim of the clock.  No.  And since you did not actually modify any arc, you didn't change the circumference of the clock rim either.  You just changed the shape of the rim.
If you can picture this, now picture a rifle barrel as positive and negative arcs.  Since the negative arcs will require milling, the resulting barrel will be lighter, BUT, the surface area will not be changed at all. You have identical positive and negative arcs.
If you tacked on fins, or cut sharp groves like a spline, you could increase the surface area.  Flutes on rifle barrels are gentle rounded, shallow groves, mostly mirrowing the arc they were milled from.
Out of here - we have beaten this to death!  Wish I knew how to draw on my screen.  PM me with an email if you wish and I can scan a drawing and email it to you.  I'll attempt to take measurements from a Remington flutted 7-08 LVSF barrel.
Somebody on the forum explained it all to me a year or two ago.  Until then I thought the surface area was greatly increased too.