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View Full Version : Barrel fluting, should I get it, accuracy, cooling?


chicoredneck
12-09-2011, 2:57 PM
This is a great little website that will answer many of these questions:
http://www.varmintal.com/aflut.htm

Keep in mind his simulation only accounts for a few factors. Barrels actually vibrate in all directions.

And read John Burns posts at this websites as he has some good info on cooling time.

http://www.longrangehunting.com/forums/f17/300-win-mag-1292/index3.html#post10142

http://www.longrangehunting.com/forums/f17/300-win-mag-1292/index4.html#post10144

and a quote from:

Theodore Karagias
President
American Rifle Company, Inc.


"Here is an interesting thought regarding a "soft-axis" and vibration and how flutes can play a role.

So long as the rifle’s center of mass does not coincide with the bore axis along which the recoil force will act, the rifle will undergo translation and rotation about its center of mass as the bullet and gas accelerate down the barrel. The angular acceleration imparted by the recoil causes the barrel to vibrate. Designing the rifle so that its center of mass coincides with the bore axis, thereby eliminating the angular acceleration responsible for much of the barrel vibration, is usually impractical, especially because the mass of the rifle changes as ammunition is consumed. We must therefore find some way to better deal with the barrel vibration.

It is conceivable that by fluting a barrel we can constrain the muzzle to vibrate at low frequency on a plane upon which lie both a “soft-axis” and the rifle’s center of mass. A low frequency is important as it offers the best chance for us to consistently pass the bullet through the muzzle while the muzzle is either at the top or the bottom of the wave characterizing its vibration.

People often assume that stiff barrels will result in better accuracy. That may be true if the barrel is stiff enough to adequately control the muzzle position during firing. But a stiff barrel will likely vibrate at higher frequency than a compliant one making it more difficult to consistently time the exit of the bullet with a unique position of the muzzle as it vibrates. When you work up a load by varying powder charge, you are effectively changing this timing. The Browning Boss does the same thing but in a different way.

Refer to Chapter 4 of Harold Vaughn’s Rifle Accuracy Facts for more on barrel vibration. No discussion of rifle accuracy can be complete without reference to Vaughn’s book.

I think a strong case can be made for improving the accuracy of a rifle by intelligently fluting the barrel to “soften it up.” As for the heating and cooling effects of fluting, I will leave that up to Bohem. He’s is undoubtedly our resident expert on heat mind mass transfer and I would like to thank him for the engineering rigor exhibited within his posts. Nice job Bohem."

The qute was ripepd from sniper's hide

killshot44
12-09-2011, 3:13 PM
Who seeks the highest level of accuracy? Benchrest competitors.

What do the winners use? Thick barrels with no flutes.

Let facts be your guide.

Rumline
12-09-2011, 6:11 PM
I don't know jack sh*t about this but from what I've read, get fluting because of the weight reduction / moving the balance of your gun to the rear, or maybe because you like the way it looks. Not because of any alleged increase in accuracy.

Thin barrels are quicker to warm up yet also shed that heat a lot quicker than thick barrels. Thick barrels are great for benchrest guys because it's easy to keep them at a consistent temperature, particularly since most benchrest shooters are not doing any sort of rapid-fire that would cause the temps to spike. Consistent temperature = tighter groups.

Richard Erichsen
12-09-2011, 8:13 PM
For most barrel makers, benchrest rifle builders and many competitive shooters, flutes are a gimmick meant to attract attention, stand out from the competition for looks or astounding marketing claims that can go on about cooling benefits, increased rigidity to promote accuracy and the likes. Some of the benefits are true up to a point, but they are fairly minor in their effect.

It doesn't cost the average barrel maker much machine time to cut flutes and since there is no dramatic result, cutting any pattern they feel like using that doesn't compromise the integrity of the barrel is fair game for some enterprising makers.

For the money, you would probably be a lot better off ordering a barrel that is made with greater precision, which usually means longer machining times, more QC and higher reject rates, a privilege you will pay for. Stainless steels are now the norm for benchrest and several other precision rifle competitions.

The type of rifling and how that rifling is cut to achieve maximum bullet stability for a given range of ammunition types is a matter of debate, as both cut rifling and button rifling have won competitions. A barrel that is of greater precision is generally air gauged, is thermally stress relieved after every major machining operation, hand lapped for a smooth bore with no burs and may be sized one or two sizes larger in diameter/contour than might be typical for that rifle in a given caliber.

Flutes are mostly just for looks, but doing something because it looks good to your eye is good enough rationale if you really like it, just don't expect flutes to transform the performance of the barrel by itself.

R

rero360
12-09-2011, 8:28 PM
CDI, thats it

chead
12-09-2011, 8:39 PM
You could calculate the rate of heat dissipation given the thermal inertia of a metal and the increased surface area provided by fluting. I won't, because I'm lazy (see: http://en.wikipedia.org/wiki/Heat_sink#Methods_to_determine_heat_sink_thermal_p erformance), but I'm pretty sure it would be incredibly minute.

problemchild
12-10-2011, 6:01 AM
Who seeks the highest level of accuracy? Benchrest competitors.

What do the winners use? Thick barrels with no flutes.

Let facts be your guide.

x2

Every one hole group rifle I have seen was not fluted or braked.

r3dn3ck
12-10-2011, 6:14 AM
An open bolt cools the hell out of a barrel. Fluting has never helped with cooling to any useful degree IME. I once fixed a dozen heat sinks (from Pentium processors, had to bend them around a mandrel to shape them) to the barrel of a very fast firing full auto .22 (when I lived in a free state and had friends with freedom toys) and that really helped with cooling but not as much as leaving the bolt open did.

chicoredneck
12-10-2011, 9:10 AM
For most barrel makers, benchrest rifle builders and many competitive shooters, flutes are a gimmick meant to attract attention, stand out from the competition for looks or astounding marketing claims that can go on about cooling benefits, increased rigidity to promote accuracy and the likes. Some of the benefits are true up to a point, but they are fairly minor in their effect.

It doesn't cost the average barrel maker much machine time to cut flutes and since there is no dramatic result, cutting any pattern they feel like using that doesn't compromise the integrity of the barrel is fair game for some enterprising makers.

For the money, you would probably be a lot better off ordering a barrel that is made with greater precision, which usually means longer machining times, more QC and higher reject rates, a privilege you will pay for. Stainless steels are now the norm for benchrest and several other precision rifle competitions.

The type of rifling and how that rifling is cut to achieve maximum bullet stability for a given range of ammunition types is a matter of debate, as both cut rifling and button rifling have won competitions. A barrel that is of greater precision is generally air gauged, is thermally stress relieved after every major machining operation, hand lapped for a smooth bore with no burs and may be sized one or two sizes larger in diameter/contour than might be typical for that rifle in a given caliber.

Flutes are mostly just for looks, but doing something because it looks good to your eye is good enough rationale if you really like it, just don't expect flutes to transform the performance of the barrel by itself.

R

I agree with most of this post. In reality, a well manufactured barrel is what makes a difference. In my experience fluting neither adds nor detracts from a rifles accuracy, if the fluting was done properly. Weight and length do, however.

In the barrels we are using for our WSSM uppers fluting shaves about 1/2 pound off of the total weight of the rifle depending on the length of the barrel. For some (such as hunters) this may be important, for others it is a detriment as they want as much weight as possible. Fluting also adds to the overall surface area of the barrel which does cause it to cool significantly faster. However, due to the decrease in mass a fluted barrel will also heat up faster than one of equal contour and length that is not fluted.

I posted the links because I felt that they were informative and interesting and thought that others would find them to be as well.

captbilly
12-10-2011, 11:53 PM
It isn't enought to look at the barrel when trying to calculate the vibrations of the muzzle. Unless you are going to bolt the receiver to a ton of solid steel, the entire rifle, and shooter, are going to move when the cartridge is fired. This is why serious target shooters spend so much time practicing a consistent hold and trigger pull, so that the rifle moves the same amount every time they shoot. When i used to shoot competitively we would readjust our sights for each of the four possitions, because each possition involved different movements of the gun and the shooter's body.

cuinmysights
12-11-2011, 10:13 AM
LWRCI M6A2 SPR flute barrel claims to solve the shortcomings of other fluted designs with their current design.

fmunk
12-11-2011, 11:39 AM
Fluting is mostly for weight while keeping some rigidity of bull or heavy barrels. It was never meant to improve accuracy of any barrel.

ADCO Firearms in Ohio does fluting. Roughly 1 week turn-around.