Fluted barrel pros/cons
- Thread starter slamman190
- Start date
lejarretnoir
CGN Ultra frequent flyer
- Location
- 162km from Connaught
I heard a theory that made claims about spiral flutes on barrels that matched the same twist as the rifling as being more accurate. So, if it is 1-10" twist 6 groove barrel the flutes would have 6 grooves with the same twist rate.
Also heard a theory that removing metal from an item strengthens it.
Another relates to mass and cooling effect. The reduction of mass speeds heating and cooling, an increase of mass slows heating and cooling.
Add fins to barrel for increased cooling effect aka the air cooled combustion engine.
Also heard a theory that removing metal from an item strengthens it.
Another relates to mass and cooling effect. The reduction of mass speeds heating and cooling, an increase of mass slows heating and cooling.
Add fins to barrel for increased cooling effect aka the air cooled combustion engine.
There are some valid concerns about fluting a barrel. Depending on how the barrel is made there are residual stresses left in it. Hammer forging (Sako, Tikka, CZ, & some Remingtons) probably leaves the most residual stress. Button (Shilen, Lilja, Hart, and many others) rifling is next, and cut rifled (Krieger, Bartlein, ...) the least. The issue is that when you cut slots in the barrel OD you release some of the stresses. This can do at least a couple of things. First, the barrel can simply distort and bend. Some barrel makers straighten their barrels in the factory. Second since you are releasing stress, the bore of the barrel can increase in diameter. Hart, and I suspect others, manage that issue by leaving the final hand lapping of the barrel (which removes as much as 0.001" until after the fluting. That way they can restore uniformity to the bore.
The other issue besides residual stress is the thickness of the barrel. Increased bore (like a 30-06 vs a .223), cuts into thickness, as does a lighter profile on the barrel. So flutes in a light sporter barrel with a big bore can be trouble. Most barrel makers set a limit on the thickness profile that they will not go below and flute.
But flutes do look good, and especially on a heavy barrel take away that piece of pipe look.
The other issue besides residual stress is the thickness of the barrel. Increased bore (like a 30-06 vs a .223), cuts into thickness, as does a lighter profile on the barrel. So flutes in a light sporter barrel with a big bore can be trouble. Most barrel makers set a limit on the thickness profile that they will not go below and flute.
But flutes do look good, and especially on a heavy barrel take away that piece of pipe look.
So in the end, fluting for a hunting rifle is a great idea, because if you are tromping around the bush all day, why carry a rifle that is heavier than it needs to be...
And of course the cool factor!
As I intend to use this rifle as my go to rifle for deer and large game, any minimal reduction in accuracy from a barrel of same size but non fluted would not really effect accuracy as far as would be needed for hunting.
Noted.
And of course the cool factor!
As I intend to use this rifle as my go to rifle for deer and large game, any minimal reduction in accuracy from a barrel of same size but non fluted would not really effect accuracy as far as would be needed for hunting.
Noted.
I agree that the heat exchange increase from fluting will be minimal, but it still exists, its more than just the increased surface area, however. Recall from simple thermodynamics that the heat flux is dependent on the thickness of the material. Fluting adds surface area, as well as decreasing the nominal thickness of the barrel. Likely we are talking such a small amount of time saved, ie you can decrease your timing between shots from 2 minutes to 1 minute 55 seconds. If you had a machine gun it might be more useful.
Removal of material does nothing but weaken the gun barrel; it can never add strength. However, removal of material at the right locations will not weaken the barrel as fast as it lightens the barrel. It all has to do with the moment of interia of the cross section of the barrel. Similar to how 'I'-beams have most of their material at the top and bottoms. Given a solid bar of the same weight per length, the I beam will be stiffer because of the higher moment of inertia. By taking a close look at the moment of inertia of a fluted barrel, it becomes apparent that fluting becomes most effective for improving stiffness when an ODD number of flutes is involved. The nominal diameter remains the same, but, the moment of inertia is increase ever so slightly and actually has a slight dampening effect on the rifle barrel. If the fluting is spiralled, it will still do the same thing, albeit while looking cooler. I cannot see how spiral fluting would be an improvement over straight flutes, other than you might get the deer to stand still for a few seconds while he admires your gun.
Removal of material does nothing but weaken the gun barrel; it can never add strength. However, removal of material at the right locations will not weaken the barrel as fast as it lightens the barrel. It all has to do with the moment of interia of the cross section of the barrel. Similar to how 'I'-beams have most of their material at the top and bottoms. Given a solid bar of the same weight per length, the I beam will be stiffer because of the higher moment of inertia. By taking a close look at the moment of inertia of a fluted barrel, it becomes apparent that fluting becomes most effective for improving stiffness when an ODD number of flutes is involved. The nominal diameter remains the same, but, the moment of inertia is increase ever so slightly and actually has a slight dampening effect on the rifle barrel. If the fluting is spiralled, it will still do the same thing, albeit while looking cooler. I cannot see how spiral fluting would be an improvement over straight flutes, other than you might get the deer to stand still for a few seconds while he admires your gun.
FWIW a slightly lighter contour will be lighter than a fluted hunting barrel and will shoot just as well.
I have played with and custom contoured barrels between#2 and #3 with more meat in the chamber and less muzzle diameter and in the end it all amounted to me be stupid and getting parted with more money....They all shot the same (good).
I like the look of flutes..Maybe the next one will get the ###y treatment.
Not from a pure strength point of view. However if you have an object of irregular shape you can improve the fatigue strength by removing material. One example might be the head of a bolt subject to reversing stress (causes fatigue). If you undercut the bolt in the area of the head it reduces the stress concentration and improves fatigue life. However a rifle barrel does not fail from fatigue. It just burns from the inside out.
It all depends on how the barrel was made. During button rifling or hammer forging (The two methods used by all factory manufacturers) a number of stresses are introduced into the steel. Custom barrels that are button rifled are baked for many hours at high temperature in order to relive stresses. It removes most but not ALL latent stress. Changes occur after stress relieving, and custom button barrels are then lapped to even out changes in the bore dimensions. Factory barrels are NOT lapped, meaning you get what you get. SOme are great, some are terrible, and the rest are in between.
When rifling is created with a button, a carbide plug is forced through the bore under roughly 25,000 pounds of force, it pushes steel aside to create rifling - and causes stress. Remington hammer forges, which consists of beating the barrel over a mandrel to create the rifling, and this also creates stresses.
When you flute a barrel, you mechanically relieve those latent stresses and it can result in a warping of the barrel. Also, it can become more evident as the barrel heats up. Dimensional inconsitencies in either the steel itself or the dimensions of the grooved flutes will cause asymetrical expansion of the steel and will result in a wandering point of impact.
Cut rifling is by far the safest way of ending up with a barrel that has a minimum of stress in the steel, but even cut barrels are vulnerable to some degree.
Honestly, I don't care for fluting, and as a long range competitive shooter I would NEVER opt for a fluted barrel, but I understand the desire to keep things light, but the only real benefit of fluting is esthetics.
When rifling is created with a button, a carbide plug is forced through the bore under roughly 25,000 pounds of force, it pushes steel aside to create rifling - and causes stress. Remington hammer forges, which consists of beating the barrel over a mandrel to create the rifling, and this also creates stresses.
When you flute a barrel, you mechanically relieve those latent stresses and it can result in a warping of the barrel. Also, it can become more evident as the barrel heats up. Dimensional inconsitencies in either the steel itself or the dimensions of the grooved flutes will cause asymetrical expansion of the steel and will result in a wandering point of impact.
Cut rifling is by far the safest way of ending up with a barrel that has a minimum of stress in the steel, but even cut barrels are vulnerable to some degree.
Honestly, I don't care for fluting, and as a long range competitive shooter I would NEVER opt for a fluted barrel, but I understand the desire to keep things light, but the only real benefit of fluting is esthetics.
gunrunner8
CGN Ultra frequent flyer
- Location
- Kamloops, B.C.
That's why the stepped barrels in front of chamber makes so much more sense, the taper can be started from a litle bit thinner dia and muzzle left bigger for the benefit of barrel stiffeness, all my barrels are countured that way. Somebody mentioned that hammer rifled barrels are no good for fluting and that's the truth. Button rifled and especialy cut rifled barrels are best for fluting but only if they are thick enough and short enough. After a bunch of them being fluted by me I have quite good idea which ones can be fluted and yes uneven numbers of flutes makes the barrel stiffer. Also the long ones and thin ones might allow the chatter and that's is the pain in the neck to eliminate.I have played with and custom contoured barrels between#2 and #3 with more meat in the chamber and less muzzle diameter and in the end it all amounted to me be stupid and getting parted with more money....They all shot the same (good).
I like the look of flutes..Maybe the next one will get the ###y treatment.
When I bought my new Cooper 6mm last year I had them flute the barrel for an extra $200. I doubt if it hurt the accuracy any as the test target was under .25". Was it worth the $200 to have something a little different then most other people,Yes. The new Browning X-Bolt I have coming in the mail next week also has a fluted barrel and it might be a few weeks until it warms up to see if it's a shooter or not but I can let you know either way.
- Location
- Somewhere on the Hudson Bay Coast
In a hunting rifle fluted barrels offer no advantage, other than cosmetic, and not everyone considers that an advantage. I have a couple of fluted barrels, and at the time I ordered them I thought they were cool, but since that time I have come to prefer the look of a smooth barrel surface. I will never again order a fluted custom barrel on a hunting rifle as weight can be controlled through the selection of the contour and length of the barrel.
In a match barrel though, there are some significant advantages to fluting. Fluting allows you to compete in a lower weight class with a larger diameter thus stiffer barrel. The flutes increase the barrel's surface area, thus aid in the speed of cooling. Fluting might increase rigidity, but it would be difficult to prove. The problem of stresses in barrel steel, whether created through fluting, rifling or other manufacturing process, is answered by the barrel maker who cryogenically treats his barrels.
In a match barrel though, there are some significant advantages to fluting. Fluting allows you to compete in a lower weight class with a larger diameter thus stiffer barrel. The flutes increase the barrel's surface area, thus aid in the speed of cooling. Fluting might increase rigidity, but it would be difficult to prove. The problem of stresses in barrel steel, whether created through fluting, rifling or other manufacturing process, is answered by the barrel maker who cryogenically treats his barrels.
My guess without doing the calculations would be that a stepped is stiffer. However, I would expect a straight taper would be the stiffest for a given total weight. And if you wanted to be fancy, then a variable depth fluting with the flute depth getting deeper toward the muzzle would make it stiffer too -- for the same total weight.
I know a lot of sheep hunters that would disagree with you. Shaving a couple ounces off here and there on a sheep rifle can make a huge difference in the long run.
If truly shaving ounces is what your trying to do fluting is a poor way to achieve that particular goal.
- Location
- Somewhere on the Hudson Bay Coast
That is certainly the current trend, although personally I think the quest for ultra light rifles has become over done. But what do I know, my idea of a hill is about 100' high. Last time I was in the Yukon, it didn't take long for me to get puffed out on what appeared to be a pretty gentle slope.
- Location
- Southern Alberta
I feel the same way. There are 100's of things to be done to reduce by an ounce here and there. An enema should drop you 1-10lbs.
But....I don't pack a rifle all over a mountain, through the valley and up the mountain, all the time HOPING I don't kill something since I'll have to pack it back too!
I look for the nearest spot that has just enough rise that I can back my truck up to, and roll my animal DOWN into the box.
When I was younger, and not so lazy, I would shoot my Deer as soon as I saw it, and I've dragged a number of them up some long and steep Coulee's.
