Barrel Stiffness, Round vs Octagonal

[Dragoon 45]

In a gunshop yesterday, I was talking to one of the employees. I was kind of looking at a Remington VTR, with the triangliar barrel. So I asked the guy I was talking to the purpose behind the triangle shape of the barrel besides cutting down on the weight and heat reduction. His reply was that the flat sides provided more stiffness to the barrel than a round barrel of the same diameter would. He further said that an octagonal barrel was much stiffer than a round barrel of the same diameter also.

I can see some advantages to the octagonal barrel over a round one: more surface area allows better barrel cooling, saves some weight, and possibily easier to mount sights on the octagonal also. But I had never heard the idea that the octagonal barrel was stiffer than the same size round barrel before. If that was the case, why aren't most of the modern barrels produced today octagonal?

Am I missing something here, or is this guy a little off in his thinking?

Thanks, I am trying to expand my knowledge a little more.

[waksupi]

I do believe this is one of those solutions, in search of a problem. I wouldn't pay extra for any of them, unless I just plain liked the configuration. As far as buying something because some salesman in a store or from a manufacturer gently wafted smoke up my anal orifice, I would pass. When is the last time you have bent a barrel? I treat some of my guns pretty rough, and have never had the problem, even with horses rolling over the rifles. In that case, I doubt that configuration will matter one whit.

[Cap'n Morgan]

His reply was that the flat sides provided more stiffness to the barrel than a round barrel of the same diameter would. He further said that an octagonal barrel was much stiffer than a round barrel of the same diameter also.

That is not correct, but it is a common misconception. What he should have said was, that a barrel with flats will be more stiff than a round barrel of the same weight! You can't compare barrel diameters directly, as a polygon contour will have two diameters; an inscribed diameter for the flats and an outscribed diameter for the corners.

[nicholst55]

Elmer Keith always said that rifles with octagonal barrels were typically less accurate than a similar rifle with a round barrel of a comparable weight. This was based on his exposure to original Sharps and other 'buffalo guns' in his youth.

I dunno if it's true or not, but Elmer sure seemed to think so.

[NickSS]

Actually way back this was true like when they made the original sharps. In fact Sharps tried to get round barrels popular but people were used to octagon ones in hunting rifles. This is due to stress risers in the metal caused by the milling needed to make an octagon barrel in those days. Of course no one knew anything about this back then. However, today octagon barrels go though a stress relief process so that these stess risers are removed to a large extent during manufacture. However, you will never see an octagon or polygonal barrel on a bench rest rifle.

[SlamFire1]

There are lots of wives tales about barrel shapes.

I recall an American Rifleman article from the 20’s, the author was using the then “magnum” of the period, a 30-06. He was hunting seal with Eskimos. The Eskimos had octagonal barreled 30-30’s from the trade store. They were making fun of his rifle as it had a round rifle barrel and the trade store told them that octagonal barrels shot harder. (Also cost more!). They were very impressed when the 30-06 went through two seals.

I believe the origin of octagonal barrels is due to primitive manufacturing. If you look at the equipment the country back woods gunsmiths had, a powered lathe was not one of these. One common technique was making barrels by twisting metal around a mandrel. Barrel steel was very soft wrought iron. It could be filed flat and it would look straight. You could pull a string and see how straight and flats were symmetrical.

[felix]

The simplest answer is the heavier the barrel the better in a gun SYSTEM. ....The best answer is the barrel SYSTEM which has the least movement at the muzzle WHEN the projectile leaves the barrel.... We are not talking about stiffness here, but instead the dynamics of the barrel (for accuracy). A round barrel will always be stiffer AT THE SAME VOLUME AND DENSITY, not counting the bore size. ... felix

[Gunlaker]

I don't kncow about stiffness, but I do know that a round barrel has more surface area for a given "diameter" than an octagonal one. But a fluted barrel will generally have more surface area than round.

To me round barrels are only nice if the first half of the barrel is octagonal :-). Fluted is even worse, and I don't have the words for a triangular barrel :-)

Chris.

[Dragoon 45]

Thanks guys, I suspected this was some sort of old wives tale.

[looseprojectile]

I once told my #2 son that I thought a fluted barrel was stiffer, stronger.
He [Mechanical Engineer] said no, it is stiffer with more material in it.
So I was wrong once.:oops:
I have had guns with nearly all configurations of barrels except the new Remingtons with the triangular barrels and have not seen the need for any preference in hunting guns other than weight.
If it is lighter most likely it is harder to get it to shoot precisely, as a general rule.
Lots of exceptions though.

Life is good

[oldracer]

Okay everyone, please use the link I have below to read ad-infinitum about barrel stiffness. As far as our black powder single shot rifles I am thinking that the way the rifling is cut and the steel has been formed and aged has more to do with accuracy than round or other barrel shape. As a test last winter I coated both round and flat sided barrels with oil to see what the sine wave down the barrel would be like. Both round 34 inch on a limited edition Pedersoli and Octagonal 34 inch Badger on a Rolling block had nearly exactly the same wave form and length after shooting. In both cases the barrels were rested on X-sticks touching the fore end wood.

http://www.riflebarrels.com/articles/barrel_making/rigidity_benchrest_rifles.htm

[Lead pot]

I have Sharps rifles with a round barrels and octagon barrels.
At one time I thought that the two round barrel Sharps shot better then the 5 octagon.
Now I cant tell the diff because some times the round barreled once shoot better and a few days later the octagon once do[smilie=l:

[Boz330]

I have Sharps rifles with a round barrels and octagon barrels.
At one time I thought that the two round barrel Sharps shot better then the 5 octagon.
Now I cant tell the diff because some times the round barreled once shoot better and a few days later the octagon once do[smilie=l:

GEEEESH I have the same problem with the same loads from day to day.

Bob

[Lead pot]

Me too, but some day I will get it figured out