barrel fluting
Barrel fluting has had me befuddled for years, especially the claim that it stiffens the barrel. It seems to me that removing material would actually weaken the barrel; a thicker barrel is stiffer than a thinner barrel. I understand the argument about how removing material increases the surface area and hence the cooling rate of the barrel, but wouldn't you have to fire a large number of shots very quickly to achieve this added benefit? And would that really be practical? Are most deer and varmit rifles fired to such a rate that the payoff would be reached?
And if increasing the surface area is the ultimate goal, wouldn't installing fins on the barrel and not decreasing its outside diameter be a smarter (if uglier) way to do that. Some WWI and WWII machine guns went that route.
If weight reduction is the main goal, why not just use a thinner barrel? Is the stiffness of the original diameter maintained even when the barrel is fluted? That would seem to be the one real argument for doing this, that a fluted barrel maintains the original stiffness while losing some of the weight.
Can anybody walk me through this?
And if increasing the surface area is the ultimate goal, wouldn't installing fins on the barrel and not decreasing its outside diameter be a smarter (if uglier) way to do that. Some WWI and WWII machine guns went that route.
If weight reduction is the main goal, why not just use a thinner barrel? Is the stiffness of the original diameter maintained even when the barrel is fluted? That would seem to be the one real argument for doing this, that a fluted barrel maintains the original stiffness while losing some of the weight.
Can anybody walk me through this?
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A fluted barrel is lighter than a barrel of equal outside diameter, and stiffer than a barrel of equal weight, and the increased surfaced area increases the ability to dissipate heat. 0 -
How does removing material from the barrel make it stiffer? I could see someone perhaps rearranging material to make a structure/object stronger, but removing material--it just doesn't make sense. If I have a metal bar that is 1/64" in diameter and a bar that is 1/2" in diameter, the thicker bar would be more resistant to bending. 0 -
it adds arches to the barrel, this allows for extra strength 0 -
That doesn't make sense. By extending your logic, I could take X piece of material, cut a bunch of arches in it, and say that it's now stronger. Why, then, don't we see all sorts of lumber and building materials being sold with arches cut all through them? How can a structure be made stronger by removing material? 0 -
Its stiffer than a barrel of equal weight. An unfluted barrel of the same weight of a fluted bull would have a much smaller diameter. The idea behind fluting is to give a barrel the stiffness of a bull barrel and the weight of a standard, light barrel. 0 -
A engineer's perspective on fluting:
These discussions on fluting are guaranteed to produce lots of controversy!
All you really need to know is that as you take material off you reduce the stiffness.
So long as the material properties remain unchanged (specifically, the material strength), you CANNOT remove material from ANY shape, and make it stronger! A clever engineer, however, can move material to make the part stronger...
Anyhow, in a humble attempt to end this controversy for once and for all, I've decided to try a cold, hard, mathematical analysis of a typical real-world situation.
Given:
* Weight is directly proportional to cross-sectional area. (Specifically, the weight is equal to the cross-sectional are times the length, times the material density.)
* Rigidity (stiffness) is directly proportional to Area Moment of Inertia.
* Surface area is directly proportional to the outside perimeter. (Specifically, the surface area is equal to the perimeter times the length.)
Both "givens" are per every basic engineering Statics text.
Test subject barrels:
Remington 700VS:
outside diameter: 0.850"
bore: .300 bore with six .308 grooves, 50% grooved
flutes: none
Cross-sectional area: 0.493 sq.in.
Area Moment of Inertia: 0.02489
Perimeter: 2.666"
Remington 700VSF:
outside diameter: 0.850"
bore: .300 bore with six .308 grooves, 50% grooved
flutes: six, 3/16" wide, 3/16" deep, full radius
Cross-sectional area: 0.312 sq.in.
Area Moment of Inertia: 0.01411
Perimeter: 4.276"
Hypothetical barrel for comparison:
outside diameter: 0.7005"
bore: .300 bore with six .308 grooves, 50% grooved
flutes: none
Cross-sectional area: 0.312 sq.in.
Area Moment of Inertia: 0.01127
Perimeter: 2.197"
Comparisons:
0.850" Fluted vs. 0.850" Plain:
Cross-sectional area (weight): 36.7% less
Area Moment of Inertia (rigidity): 43.3% less
Perimeter (surface area): 60.4% more
Conclusion: the fluted barrel is much lighter, much less rigid, and has much more surface area than a solid barrel of the same diameter.
0.850" Fluted vs. 0.7005" Plain:
Cross-sectional area (weight): *same*
Area Moment of Inertia (rigidity): 25.2% more
Perimeter (surface area): 94.6% more
Conclusion: the fluted barrel is significantly more rigid, and has much more surface area than a solid barrel of the same weight.
Notes:
* All section properties are courtesy of the 2D Properties module of Ashlar Vellum 3D version 2.70 (my favorite CAD program), based on my layout of the sections.
* Measurements of the 700VS were taken from an actual 700VS from my personal collection.
* I didn't actually have a 700VS on hand, but have recently compared one to a 700VS side by side (while deciding which to buy), and verified that the barrel outside diameters are the same. Flute dimensions are approximate, but should be fairly accurate. After ten years as an engineer, I have a good eye for dimensions; I know for sure that the flute width was much more than 1/8", and definitely less than 1/4"; 3/16" should be quite close. Likewise, I noted for certain that the flutes were full radius, and deep enough that the radius started approximately 3/32" below the outside diameter. Despite any minor errors, the fluted barrel described is certainly representative of the Real World, and the trends are quite clear from the analysis; the effects of fluting are significant. A 1/16" here or there would not noticeably change the results.
* The weight and surface area comparisons hold true only for the fluted portion of the barrel. On every fluted barrel I've seen, the fluting does not begin until well forward of the chamber (6"-9"), and ends from 1"-4" from the muzzle. For example, on the Remington barrels presented, only approximately 65% of the barrel is actually fluted, so you will only realize ~65% of the weight savings and surface area increase. Also, I've seen some fluted barrels where the fluting is more shallow and/or narrow than the examples presented. Hence, the effects of the fluting would be less than reported above.
* I also did a quick analysis of a fluted barrel with shallower flutes; I won't present the entire analysis here, but in summary, a barrel of the same weight also had a larger diameter, and the differences in stiffness and surface area were simply less pronounced than the barrel detailed above. Extrapolating: as the flutes become smaller, the effects diminish; as the flute dimensions approach zero, the fluted barrel (and the barrel of the same weight as the fluted barrel) simply becomes the original bull barrel, and there's no effect. Conversely, as the flutes get larger, the effects become more pronounced; eventually, though, one would run up against a geometrical limit (the flutes colliding, or reaching the bore). Under NO geometrically possible conditions can flutes make a barrel MORE rigid than a plain, unfluted barrel of the same diameter.
* Before someone asks: no, the number of flutes has no real effect on these conclusions. Four (or fewer) flutes of the same size would simply remove less material and hence reduce the effects shown. Eight (or more) flutes might increase the effects, but would tend to collide more easily (less room for material between the flutes), so in reality they would tend to have less depth, and hence limit the effects achievable.
--Gryffin
gryffin@gryffnet.com0 -
Good job.
Doug0 -
quote:Originally posted by bondai
A engineer's perspective on fluting:
These discussions on fluting are guaranteed to produce lots of controversy!
All you really need to know is that as you take material off you reduce the stiffness.
So long as the material properties remain unchanged (specifically, the material strength), you CANNOT remove material from ANY shape, and make it stronger! A clever engineer, however, can move material to make the part stronger...
Anyhow, in a humble attempt to end this controversy for once and for all, I've decided to try a cold, hard, mathematical analysis of a typical real-world situation.
Given:
* Weight is directly proportional to cross-sectional area. (Specifically, the weight is equal to the cross-sectional are times the length, times the material density.)
* Rigidity (stiffness) is directly proportional to Area Moment of Inertia.
* Surface area is directly proportional to the outside perimeter. (Specifically, the surface area is equal to the perimeter times the length.)
Both "givens" are per every basic engineering Statics text.
Test subject barrels:
Remington 700VS:
outside diameter: 0.850"
bore: .300 bore with six .308 grooves, 50% grooved
flutes: none
Cross-sectional area: 0.493 sq.in.
Area Moment of Inertia: 0.02489
Perimeter: 2.666"
Remington 700VSF:
outside diameter: 0.850"
bore: .300 bore with six .308 grooves, 50% grooved
flutes: six, 3/16" wide, 3/16" deep, full radius
Cross-sectional area: 0.312 sq.in.
Area Moment of Inertia: 0.01411
Perimeter: 4.276"
Hypothetical barrel for comparison:
outside diameter: 0.7005"
bore: .300 bore with six .308 grooves, 50% grooved
flutes: none
Cross-sectional area: 0.312 sq.in.
Area Moment of Inertia: 0.01127
Perimeter: 2.197"
Comparisons:
0.850" Fluted vs. 0.850" Plain:
Cross-sectional area (weight): 36.7% less
Area Moment of Inertia (rigidity): 43.3% less
Perimeter (surface area): 60.4% more
Conclusion: the fluted barrel is much lighter, much less rigid, and has much more surface area than a solid barrel of the same diameter.
0.850" Fluted vs. 0.7005" Plain:
Cross-sectional area (weight): *same*
Area Moment of Inertia (rigidity): 25.2% more
Perimeter (surface area): 94.6% more
Conclusion: the fluted barrel is significantly more rigid, and has much more surface area than a solid barrel of the same weight.
Notes:
* All section properties are courtesy of the 2D Properties module of Ashlar Vellum 3D version 2.70 (my favorite CAD program), based on my layout of the sections.
* Measurements of the 700VS were taken from an actual 700VS from my personal collection.
* I didn't actually have a 700VS on hand, but have recently compared one to a 700VS side by side (while deciding which to buy), and verified that the barrel outside diameters are the same. Flute dimensions are approximate, but should be fairly accurate. After ten years as an engineer, I have a good eye for dimensions; I know for sure that the flute width was much more than 1/8", and definitely less than 1/4"; 3/16" should be quite close. Likewise, I noted for certain that the flutes were full radius, and deep enough that the radius started approximately 3/32" below the outside diameter. Despite any minor errors, the fluted barrel described is certainly representative of the Real World, and the trends are quite clear from the analysis; the effects of fluting are significant. A 1/16" here or there would not noticeably change the results.
* The weight and surface area comparisons hold true only for the fluted portion of the barrel. On every fluted barrel I've seen, the fluting does not begin until well forward of the chamber (6"-9"), and ends from 1"-4" from the muzzle. For example, on the Remington barrels presented, only approximately 65% of the barrel is actually fluted, so you will only realize ~65% of the weight savings and surface area increase. Also, I've seen some fluted barrels where the fluting is more shallow and/or narrow than the examples presented. Hence, the effects of the fluting would be less than reported above.
* I also did a quick analysis of a fluted barrel with shallower flutes; I won't present the entire analysis here, but in summary, a barrel of the same weight also had a larger diameter, and the differences in stiffness and surface area were simply less pronounced than the barrel detailed above. Extrapolating: as the flutes become smaller, the effects diminish; as the flute dimensions approach zero, the fluted barrel (and the barrel of the same weight as the fluted barrel) simply becomes the original bull barrel, and there's no effect. Conversely, as the flutes get larger, the effects become more pronounced; eventually, though, one would run up against a geometrical limit (the flutes colliding, or reaching the bore). Under NO geometrically possible conditions can flutes make a barrel MORE rigid than a plain, unfluted barrel of the same diameter.
* Before someone asks: no, the number of flutes has no real effect on these conclusions. Four (or fewer) flutes of the same size would simply remove less material and hence reduce the effects shown. Eight (or more) flutes might increase the effects, but would tend to collide more easily (less room for material between the flutes), so in reality they would tend to have less depth, and hence limit the effects achievable.
--Gryffin
gryffin@gryffnet.com
Your science is sound. Be careful, people around here hate scientific fact, especially if it conflicts with something they read in the Bible or heard from Toothless Joe up at the auto parts store.0 -
Fluting is designed to reduce the amount of cash in the suckers wallet. By reducing the hip pocket weight and volume the sucker is made to think he's smart.
As far as heat disapation goes, the majority of the heat is generated in the chamber/throat area, and this area remains unfluted on most (all?) fluted barrels. As Doug Shilen says, by the time the increased heat disapation potential has a effect, your barrel is already to hot.
As the OP noted, finning the chamber and begining of the barrel will have a much better cooling effect than fluting near the muzzle ever will.0 -
As a fellow engineer and gunsmith I have to agree with Bondai's justification. 1 + 1 always = 2 even though the justifcation of the hypothasis is lengthy and dry...
Paul
Mountain Magic Gunsmithing0 -
quote:Originally posted by Tailgunner1954
Fluting is designed to reduce the amount of cash in the suckers wallet. By reducing the hip pocket weight and volume the sucker is made to think he's smart.
As far as heat disapation goes, the majority of the heat is generated in the chamber/throat area, and this area remains unfluted on most (all?) fluted barrels. As Doug Shilen says, by the time the increased heat disapation potential has a effect, your barrel is already to hot.
As the OP noted, finning the chamber and begining of the barrel will have a much better cooling effect than fluting near the muzzle ever will.
Tailgunner nailed it.0 -
barrel harmonics are changed as the barrel gets hot and there will be changes in accuracy, point of impact and trajectory. Thats a proven fact. Chamber heat does not play as big a part in the barrel harmonics as does the muzzle back 2/3 of the barrel. Fluting reduces the heat and allows the barrel to cool quicker because there is less material to ratain the heat.
Whether it is worth that much to the average shooter I dont know.0 -
the main reason we use it in BR competition is to reduce weight. The reduced weight allows for longer or fatter barrels while we still make the 16.5lb or 17lb weight limit.
by the time cooling effects are noticed,..the barrel will be hot enough to light a match on.
fluting can be used to open up a bore if the blank was too tight in the bore area. By fluting the exterior, the interior will expand to a more workable dia. This is ONLY assuming the bore was too tight to be useable.
as for ridgidity,..anything in the bull barrel dia will be more than ridgid enough,..and if the blank was properly stress releived, there will be no flyers (or very insignificant ones) when the barrel heats up. larger barrels yield more surface area, which in turn makes a larger "heat sink" for the heat. they take longer to heat up, but longer to cool down as well,...so the flutes mayyyyy help in some miniscule amount. I have both,..and don't see any accuracy differences.0 -
Thank you, thank you, thank you to all who replied, especially to Bondai. That really cleared it up. 0 -
BUT Bullzeye, say what you want about the Bible, Darwin, science books in general and physics and engineering in particular, but don't ever be dissing Joe who was never wrong about nothing, no time, not once.
Dissing Joe could put you in a world of hurt brother, have to open a barrel of kickass on you.[:(!][:(!][:p]0 -
quote:Originally posted by Tailgunner1954
Fluting is designed to reduce the amount of cash in the suckers wallet. By reducing the hip pocket weight and volume the sucker is made to think he's smart.
... but it allows you to be like Jethro [}:)]!0
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