Fluted or not?

SKS Ray

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I'm thinking of getting a Savage Precision Carbine in .308 but I've seen two versions available. Fluted barrel and standard heavy barrel.

Aside from weight, what advantages do both have?
 
A fluted barrel will cool quicker, a heavier barrel will be more rigid.

If the fluted barrel was as heavy as the bull barrel, it would be both more rigid, and cool quicker.

There are also harmonics issues, but probably several other variable make that hard to compare.
 
And normally cost.

What is the cost difference?

I ask because if you say that cost doesn't matter, then you are a fool. For $400 you could put a quality aftermarket barrel on a Savage that would put both of them to shame.

Also, I used to own a Savage 10-FCP McMillan with a bull barrel. I got rid of it because as a lefty, I wanted a lefty bolt gun. The 10 FCP shot like a dream and I really hated to sell it.

I got a 10 FCP-K with a fluted bull barrel. The fluting is so so shallow that its really just for looks. The gun doesn't feel noticeably lighter and any change in rigidity or cooling is too minimal for any human to perceive.

Remember, a bull barrel will do better if you intend to shoot a string of several shots over a relatively short period of time. Traditional skinny hunting barrels will have their point of impact shift as the barrel heats up.

My 308 Browning A Bolt Micro starts to walk after two rounds. My Savage was rock solid over 20 rounds as quickly as I could shoot them.

Don
 
A fluted barrel will cool quicker, a heavier barrel will be more rigid.

From what I have read that is not universally true. Some manufacturers run spiral fluting in the opposite direction of the rifeling. It is done to counter the rotational torque the bullet applies to the barrel when traveling through it. It is supposed to add rigidity and lessen the flex/whip in the barrel when fired. They will also cool faster thanks to the increase in surface area.
 
From what I have read that is not universally true. Some manufacturers run spiral fluting in the opposite direction of the rifeling. It is done to counter the rotational torque the bullet applies to the barrel when traveling through it. It is supposed to add rigidity and lessen the flex/whip in the barrel when fired. They will also cool faster thanks to the increase in surface area.

That one sounds made-up to me.
 
I'll see if I can track down the article I read it in. Either way the physics of the torque applied to the barrel is undeniable. Equal and opposite force. Every time you fire you rifle the barrel essentially wants to unwind itself because of the force applied to the rifling by bullet. Obviously it doesn't because it would take more force than it does to spin the bullet. So the bullet spins. But an equal amount of force is applied to both the barrel and the bullet. It is the same principal behind screw motors.

As for how effective running the fluting in the opposite direction is or isn't I can't say. Obviously I haven't run any lab tests, but the principal seems sound. Though it might be one of those things that doesn't have any practical effect until you get in to seriously large projectiles.

A quick search didn't turn up the article I referenced but I did find this. I'll keep looking for it.

The barrel is spiral-fluted in the opposite direction of the rifling in the barrel. When a bullet is fired through a rifled barrel, it exerts tremendous pressure in the direction of the rifling’s rotation, as the bullet is squeezed and spun under incredible acceleration. In the QX-04, the barrel is locked against surfaces towards the front of the spiral grooves. When the cartridge is fired, the slide wants to move rearward, but it cannot do so against the grooves in the barrel. The bullet, while it is in the barrel, is torquing the barrel in the opposite direction of the spiral grooves, preventing rotation of the barrel and therefore locking the slide against the angled surfaces of the spiral. When the bullet leaves the barrel, the rotational force on it is dramatically reduced, and the slide can rotate the barrel to unlock, through residual gas pressure. Clever, isn’t it - See more at: http://www.thefirearmblog.com/blog/...delayed-blowback-pistol/#sthash.O9skdQ4e.dpuf
 
From what I have read that is not universally true. Some manufacturers run spiral fluting in the opposite direction of the rifeling. It is done to counter the rotational torque the bullet applies to the barrel when traveling through it. It is supposed to add rigidity and lessen the flex/whip in the barrel when fired. They will also cool faster thanks to the increase in surface area.

Traditionally removing material does not add to rigidity. [rolleyes]

Unless you're making a bunch of triangles (trusses) and circles (fillet), because sharp corners are naturally weak and prone to cracking. While we are really speaking about hoop stress, torque, and the tension load on the barrel; by decreasing the wall thickness with flutes will not increase rigidity.

Take 2 identical barrels - turn one down to be fluted - the minimum cross sectional area has been reduced. Therefore the tensile strength, as well as the harmonics of the barrel will be different. By how much, will depend on the depth of cut & pattern.
 
Traditionally removing material does not add to rigidity. [rolleyes]

Unless you're making a bunch of triangles (trusses) and circles (fillet), because sharp corners are naturally weak and prone to cracking. While we are really speaking about hoop stress, torque, and the tension load on the barrel; by decreasing the wall thickness with flutes will not increase rigidity.

Take 2 identical barrels - turn one down to be fluted - the minimum cross sectional area has been reduced. Therefore the tensile strength, as well as the harmonics of the barrel will be different. By how much, will depend on the depth of cut & pattern.

http://www.rifleshootermag.com/gunsmithing/gunsmithing_rsgunsmith1/

The latest trend in barrels, beside cryogenic treatment either during the manufacturing stages or as an aftermarket process, is fluting. There’s really no controversy about fluting; it works. Fluting a barrel definitely lightens it, stiffens it and cools it faster because it exposes so much more surface area. Because a certain wall thickness must be maintained for safety reasons, however, a barrel must be of a heavier contour than normal and the flutes can only be so deep.
 
If you were to add flutes to a barrel, it will not be as stiff as it was before you fluted it.
A fluted barrel does have a better strength to weight ratio, so you could have a fluted barrel that is stiffer and lighter, but the major OD of the flutes would have to be bigger (hence you can't stiffen Ann existing barrel by removing material)

Sent from my SCH-I545 using Tapatalk
 
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Its clear that some of you all need to better understand some basic physics.

Its also clear that some of you already understand this. But I'll add her in hopes of helping those who are physics challenged.

Removing material from a barrel will never:

1) make it stiffer
2) make it heat up more slowly

Its just not possible. With less mass, each unit of remaining mass must absorb more heat. So the less massive barrel heats up more with each shot.

With that said, fluting can increase rigidity for a given weight. But you have to understand how and why.

lets say you have a 1" barrel that weighs 5 lbs

You can make a stiffer barrel if you start with a 1.5" barrel, which unfluted would weigh 11.75 lbs, and then flute it until it weighed 5 lbs, it would be stiffer than a solid 1" barrel. Like others have said, this is because it would allow the use of a blank with a larger OD.

Back to the topic of heating. Fluting removes mass from the barrel, but increases surface area. So with less mass, the barrel would heat faster. Period, there is no arguing this.

But once it reached a certain temp, it would dump heat into the air faster because of the greater surface area.

Again, the 1.5" barrel fluted down to 5 lbs would in all cases cool better since it has the same mass, but far greater surface area.

In reality, most fluting is not this effective because its not done deeply enough to make much of a difference.

One other thing. Sprial fluting, since it has a component that cuts cross the barrel, HURTS rigidity more than straight fluting. Spiral fluting is all about sex.
 
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One other thing. Sprial fluting, since it has a component that cuts cross the barrel, HURTS rigidity more than straight fluting. Spiral fluting is all about sex.

I get what you're saying, but how would the static "sag" of a barrel come into play?

Comparing two barrels of the same working dimensions, but with one being lighter via fluting, would the heavier, stiffer barrel bend less at rest than the lighter, fluted barrel?
 
If you were to add flutes to a barrel, it will not be as stiff as it was before you fluted it.
A fluted barrel does have a better strength to weight ratio, so you could have a fluted barrel that is stiffer and lighter, but the major OD of the flutes would have to be bigger (hence you can't stiffen Ann existing barrel by removing material)

Sent from my SCH-I545 using Tapatalk

This.

Fluting adds rigidity as compared to a barrel of the same weight. It typically decreases weight and adds back some of the rigidity that the original full barrel had. Think the "blood groove" added into a sword. Decreases weight (weaker) but adds back some of the rigidity while keeping wieght low.
 
And normally cost.

What is the cost difference?

I ask because if you say that cost doesn't matter, then you are a fool.

Don

Its clear that some of you all need to better understand some basic physics.

Its also clear that some of you already understand this. But I'll add her in hopes of helping those who are physics challenged.

I have to ask, do you deliberately try to word all of your replies to be insulting to everyone that reads them, or are you really convinced that you are so much smarter and more experienced than everybody here that the mere fact that you have to explain something makes all of us who read it, beneath you ?

But please, continue the insulting, condescending replies. It is very entertaining.
 
http://www.snipercountry.com/articles/realbenefitsbarrelfluting.asp

Mid way down. similar rifle barrels (one fluted and one not), and one smaller contour.

Leave it to the engineers.

Results



  1. 12 BVSS Fluted (OD 0.850") versus 10 FP Plain (OD 0.850")
    • Weight: 38% less
    • Stiffness (as a function of Moment of Inertia): 43% less

    The fluted barrel is much lighter, much less rigid, but has much more surface area than a solid barrel with the same overall outside diameter.
  2. 12 BVSS Fluted (OD 0.850") versus Light Varmint (OD 0.700")
    • Weight: Same
    • Stiffness (as a function of Area of Moment Inertia): 25% more

    The fluted barrel is much more rigid, and has much more surface area than a solid barrel of the same weight.

Traditionally removing material does not add to rigidity. [rolleyes]

Unless you're making a bunch of triangles (trusses) and circles (fillet), because sharp corners are naturally weak and prone to cracking. While we are really speaking about hoop stress, torque, and the tension load on the barrel; by decreasing the wall thickness with flutes will not increase rigidity.

Take 2 identical barrels - turn one down to be fluted - the minimum cross sectional area has been reduced. Therefore the tensile strength, as well as the harmonics of the barrel will be different. By how much, will depend on the depth of cut & pattern.
 
Fencer, I apologize if I insulted you or anyone else.

But blindly parroting what people in the gun press write, when often they don't understand the basics of Newtonian physics doesn't get anyone anywhere.

Clearly there are some guys here who know a lot more than me. Probably real MEs, vs myself who left engineering school after 2 years, during which time I was able to get in one class on statics and one on strength of materials.

It is incredibly frustrating to hear people keep saying that removing material from a barrel makes it stiffer.

If everything else is held constant (like the specific heat of absorption of the fluid its in, for example air vs water) the amount of heat an object can dump (convect, conduct, or radiate) out depends on 2 things.

1) surface area
2) delta T - or the difference in temp between the object and the fluid its in.

You drew a distinction between a barrel heating slower and a barrel cooling faster. Sure there is a difference in theory. But in reality what we really care about is a barrel's ability to shoot and maintain accuracy. Either way its a good point.

I'll take two extremes to make your point.

1) you fire 10 rounds in 30 seconds. - the heavier unfluted barrel will do better because it has more mass and heats less. The timeframe is too short for any cooling to happen regardless of the barrel shape. Here mass wins.

2) You fire 2 rounds a minute for 30 minutes. In this case, its not about mass absorbing heat, but more about dumping heat. In this case a fluted barrel could show an advantage provided its about as massive as the plain barrel.
 
I get what you're saying, but how would the static "sag" of a barrel come into play?

Comparing two barrels of the same working dimensions, but with one being lighter via fluting, would the heavier, stiffer barrel bend less at rest than the lighter, fluted barrel?

Its not so much about static sag. That can be compensated for. Its more about rigidity in general and its benefits. All else being equal, more rigid is always better. So if you are going to flute, why not flute longitudinally?
 
Its not so much about static sag. That can be compensated for. Its more about rigidity in general and its benefits. All else being equal, more rigid is always better. So if you are going to flute, why not flute longitudinally?

I've read some test results from modeling, with regard to fluted vs bull, and the model calculated the sag and resultant harmonics. There was a difference in the results, but I've not read of any physical tests that compare the two. I suppose there might be a practical application, if one is shooting prarie dogs @ 400yds.
 
Fencer, I apologize if I insulted you or anyone else.

In fairness, I may have been overly critical. But I do want to point out that your reply was a stand up thing to do. It's not often that someone who is obviously as knowledgeable as you, will bother to apologize. It is commendable and speaks highly of your character.

I have been around here for a while and have learned a great deal from your posts, on many subjects. Maybe I should stop being such a pussy. [grin]
 
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