Fluted barrel
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WestKentucky
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Supposedly the best of both the heavy barrel for rigidity (which equates to less harmonic whip) and a lighter contour barrel (weight) but my experience is also that its biggest selling point is that it looks cool. I don’t really see any difference in accuracy because the gun is better than me, and I struggle to notice a couple ounces on a 10 pound rifle.
small town life
Member
Factory firearms that came fluted I have are 110's in 300wm and 338lm. All shoot great, but haven't tried at an extended range. I do have 1 custom ar barrels and 1 custom barrel barrel that's fluted(untested at this time). Some say you loose accuracy and others say you don't. Weight savings can very depending on length, type and amount of flutes. I'll need testing before being able to get a conclusion or concensus.
Hooda Thunkit
Member
Oddly enough, my understanding was that the whole reason was to increase surface area to aid barrel cooling.
IDK, perhaps it's just for looks.
lysanderxiii
Member
Longitudinal fluting will make a barrel stiffer, without a large increase in weight. This is the primary reason it is done.
Barrels cool through two means, convection and radiation, both of which are improve with increases in surface area. However, most current fluted barrels don't have those tall parallel sided fin-like flutes that maximize surface area, they have relatively shallow cuts made with a ball-end cutter. The surface area increase is slight.
I have no idea what any of that high tech language means except if you don't understand it leave it alone
Given two otherwise identical barrels that have the same overall diameter.
The fluted one will be lighter and less stiff. There's less metal in the cross section so there's less stiffness and there's less metal overall so it will be lighter..
The fluted one will heat up more quickly. Less material to heat up means faster heating all else being equal.
The fluted one will cool down a bit more quickly. It has more surface area and will lose heat faster to the air.
Given two otherwise identical barrels that are the same weight.
The fluted one will be stiffer. The fluted one will have to be larger in overall diameter to keep the weight the same and there's a strength benefit to having the larger diameter.
They will heat up at the same rate. The heating is independent of the fluting and the amount of material to heat up is the same.
The fluted one should cool down a bit more quickly since it has more surface area.
The fluted one will be lighter and less stiff. There's less metal in the cross section so there's less stiffness and there's less metal overall so it will be lighter..
The fluted one will heat up more quickly. Less material to heat up means faster heating all else being equal.
The fluted one will cool down a bit more quickly. It has more surface area and will lose heat faster to the air.
Given two otherwise identical barrels that are the same weight.
The fluted one will be stiffer. The fluted one will have to be larger in overall diameter to keep the weight the same and there's a strength benefit to having the larger diameter.
They will heat up at the same rate. The heating is independent of the fluting and the amount of material to heat up is the same.
The fluted one should cool down a bit more quickly since it has more surface area.
papajim2jordan
Member
Would such a barrel on a handgun be called a piccolo? I bought used, a Rem. 700 .308 with a fluted barrel. It loves 165/168g bullets best (often ragged hole). 110g come in at about 3/4". It is kind of heavy, even with the flutes. It is a 1:11.25 or some such silly number twist. Will not stabilize bullets above 165/168 at sub speeds, but I digress...
lysanderxiii
Member
I made a slight mistake, this should read:
"Increasing the diameter will make the barrel stiffer, adding flutes will reduce the weight while also reducing the stiffness slightly. How much it changes depends how much the diameter increases and the exact profile of the flutes."
Shallow flutes don't really accomplish much.
It depends on what you want. Fluting will reduce barrel weight without dramatically reducing barrel stiffness. A thin barrel profile like those used on the Remington Mountain rifle or Winchester Featherweight can be very light, but they are not as stiff and accuracy is not going to be as good as a heavier weight barrel. Especially after more than 2-3 shots as they heat up.
You can take a standard sporter weight barrel and cut flutes in it to get the weight down to the same as the Featherweight or Mountain rifle and still retain MOST of the barrel stiffness and accuracy.
I don't think a fluted barrel will be quite as stiff or accurate as the same barrel unfluted. But everything else being the same I'd rather see the weight reduction coming from a fluted barrel instead of a thinner barrel profile.
If pure accuracy is your goal and weight reduction isn't a concern, then stay with non-fluted barrels. For what I do, I like a fluted barrel.
You can take a standard sporter weight barrel and cut flutes in it to get the weight down to the same as the Featherweight or Mountain rifle and still retain MOST of the barrel stiffness and accuracy.
I don't think a fluted barrel will be quite as stiff or accurate as the same barrel unfluted. But everything else being the same I'd rather see the weight reduction coming from a fluted barrel instead of a thinner barrel profile.
If pure accuracy is your goal and weight reduction isn't a concern, then stay with non-fluted barrels. For what I do, I like a fluted barrel.
lightman
Member
Any advantages are very minimal but I think they look sexy! I have a few rifles with fluted barrels.
Varminterror
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Varminterror
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I did some measuring and mathing yesterday, described in the other thread, linked above, which showed the fluted barrel I have on my Savage 12 BVSS was 8% lighter and had 8% increased surface area over the same contour if it had not been fluted.
Comparatively, this fluted straight taper "standard target" contour barrel with .82" muzzle has the same surface area as a barrel 1.3lb heavier with a muzzle diameter of 0.98" (29% heavier barrel) which would be even heavier than an "MTU" contour and almost a straight cylinder, a VERY heavy contour, but has the same weight as a barrel with a muzzle diameter of 0.74", which is a "Light target" contour with 12% less surface area. Stiffness of a Standard Target with the weight of a Light Target and the cooling surface of an MTU contour... can't beat that.
Comparatively, this fluted straight taper "standard target" contour barrel with .82" muzzle has the same surface area as a barrel 1.3lb heavier with a muzzle diameter of 0.98" (29% heavier barrel) which would be even heavier than an "MTU" contour and almost a straight cylinder, a VERY heavy contour, but has the same weight as a barrel with a muzzle diameter of 0.74", which is a "Light target" contour with 12% less surface area. Stiffness of a Standard Target with the weight of a Light Target and the cooling surface of an MTU contour... can't beat that.
Jim Watson
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I had one of those, the flutes were so shallow, I would not have thought they made even an 8% difference.
Varminterror
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The math is pretty simple. 75 thou flute depth on a barrel 820 thou deep even with only a 224 thou bore doesn't look very deep, obviously less than 10% of the barrel diameter and 1/3 of the bore dia, but the math is simple. Ellipse Area and Circumference calculators are available online, the area formula is pretty simple, the circumference approximation formula is more complex, but the calculators are widely available. The math once you have the cross-sectional area and the circumference of the hemi-ellipse is super simple.
Hooda Thunkit
Member
For some. Some folks revel in that stuff.
I remember years ago I took a guy to a rock crushing plant. BIG chunks in one end, smaller rocks come out the other off the end of a belt, in a big pile.
Guy looks at the pile for a bit, turns to me and says 'Tell me the size of the small rocks, I'll tell you the angle of the sides of the pile.'
Yeesh.
Varminterror
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Yup, lol, I've also done a lot of that kind of design work around the "angle of repose," aka, "the angle of the sides of the pile." It always excites a safety manager when you warn employees about impending pile collapses too, when a little moisture helps certain products pile steeper than it naturally should - it took a pile collapse burying 6 employee vehicles at one of my sites before they started believing the science.
But these surface areametric and volumetric calcs for the fluting is really simple stuff. High school geometry level stuff (probably Middle School level stuff at most prep schools), and as I mentioned, there are online calculators to use for the ellipse circumference and area. 16 lines in Excel with 8 inputs and 8 formulas, 2 Goal Seek operations for the comparative analysis... it took longer to type this response than do the calcs.
jmorris
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Thats the easiest way to calculate the subject.
Then they can counter and say, "we will add the weight back in diameter until the point of diminishing returns, to regain stiffness and still save a little weight for all the effort."
JohnJak
Member
Feeling Groovy.
lysanderxiii
Member
Calculating the mass, surface area, and stiffness is pretty straight forward. However, calculating the heat rejection rate is a lot more complicated. Just looking at radiation, flutes will have two surfaces facing each other, so some heat radiated off one face will be reabsorbed by the opposing face. How much depends on the spacing the angle between the two faces, and a few other things. Then can you throw in convective cooling . . .
Varminterror
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Thermodynamically, this does not make any sense at all. The only means by which this can be possible is if the steel surface on one side of the flute is hotter than the steel surface on the other, otherwise we have no driving force for heat transfer from the air INTO the steel. Steel hotter than air = a thermal gradient = heat transfer. But we know the air isn't reaching the same temperature as the steel (no LMTD to drive transfer), otherwise the transfer would cease. We know the air isn't becoming HOTTER than the steel (negative LMTD in the direction of the transfer), so we're not heating the air with any part of the flute which could bounce back towards the other side.
We CAN see stagnant air reduce the temperature difference between the surface and the air, and slow or even stall the heat transfer, if the heated air cannot move away from the hot steel, but this doesn't put heat back into the steel - the hottest the air can get will be the surface temperature of the steel, and the transfer only happens away from the hotter surface - with an asymptotic approach to ZERO temp difference. This is generally a concern, for example, for tight fitting stocks, for barrel (especially flutes, or troughs in the barrel channel) where the stock is too tight to allow convection by the hot air expanding as well as moving naturally upwards as it heats - hence ventilated handguards and wide free-float around barrel channels.
We're really not even talking about enough fin height or surface area to promote a temperature gradient between the bottom of the flute belly (minor diameter of the barrel surface) vs. the outer diameter of the non-fluted portion. The transfer from steel to air is much slower/harder than transmission within the steel, so we REALLY can't promote a thermal gradient from the surface of one side of a flute to another surface of the flute. Heat ONLY travels where thermal gradients exist, and heat will NOT naturally transfer (or "reabsorb") from a cooler material to a hotter one. That's just not how thermodynamics work.
