Brent, 

    You seem to have somehow missed the point of my comment about custom rifles.  If the barrels of Pope, Schoyen, et al would have shot better with a barrel profile that was of ANY shape, that's likely what they would have used.  For instance, I've never heard of Pope making a 7 sided barrel although he was quite concerned about the INSIDE of the barrel.  He sometimes bought pre-drilled barrel stock from the big companies and worked from there...so we see, for instance, octagon Winchester marked barrels also marked "rifled by HM Pope."  BTW, one of Pope's own pet rifles had a barrel with an unfinished round contour IIRC, referred to as "dog fight."

    What I meant to imply, but maybe should have stated more succinctly, was that the octagon barrels we all seem to love (and yes, several of my favorite rifles wear them!) are really just a styling throwback and have little or no effect on the shootability of the rifle.  The additional machining, if done haphazardly, MAY even introduce additional stresses into the barrel's steel, but it PROBABLY has no effect on stiffening or cooling, or whatever...it is pretty much cosmetic nowadays, and if you want to make it look pretty (as I sometimes do) have at it; but don't expect improved performance out of this feature.

    On the other hand, if you want cooling with stiffness and other benefits from the exterior of the barrel, the current research suggests spiral or straight fluting, a larger knob left on the muzzle end, or even a reverse taper.  Those methods are outside the scope of this question and get their own thread (and hoots from the traditionalists!   )

Green Frog

To quote the gambler, "You paid to see the cards, lessons cost extra."  Before you keep tugging at this thread, please read and think about my WHOLE original answer and what it means, because I answered the question of why they started making octagon barrels in the old days...that was the way to make a finished surface while lacking sufficient machines to make a finely finished round barrel.  This information came to me from Robert Carr, an apprentice from the historic shop of Hacker Martin (flintlock builder of the early to mid-20th century.)

If you want an extended history of this topic, read and think about what each of the respondents has said and then read some of the commonly available resources.  When you can add to or refute what has been said, contribute it.  If you just want to stir the pudding, please go to a cooking forum.

Green Frog

"probably no rifle barrel quite so difficult as a Rigby"

Perhaps, but some cheat by milling a dovetailed pocket and driving in an insert. And then say that's how the originals were done

Note that, for the same amount of metal, and hence weight, the octagonal section is stiffer than the round.
Fred.

MartiniBelgian wrote on Aug 10^th, 2007 at 12:21pm:


I'm in total agreement with the above, I might add that a round tube resist deflection much better than any other shape.

In this world of shooting from a rifle barrel, when I have questions about what does it take to be the most capable for accuracy, I've always cheated and asked the best barrel makers of the day. I can't remember a single one since 1967 that has ever told me an octagonal.

I know that the people at the extreme end of peak accuracy, don't seem to be screwing octagonal barrels to their receivers. For what little that will mean to some here.

sometime I'll have to do a check but I'm willing to be that a lot of the top bench shooters at EG are using round short heavy barrels.    I think its been pretty well estabilished that as far as most modern propellents go shorter and stiffer is more productive than longer barrels.

however since we are into BOTH precision and tradition, we still see a lot of the octogonal barrels, particularly for the offhand and iron sighted guns where other factors probably out weigh the +/_ factors of round vrs octogon.

I believe you said "of equal weight".  The diameter of a round barrel that is equal in weight to an octagon barrel that is 1" across the flats will be greater than 1".   

Brent

Fred is absolutely correct, and I'll add that the orientation of an octagon makes no difference to it's bending stiffness. Same goes for fluted barrels as long as the flutes are evenly spaced.

I don't know what effect it has on torsional stiffness.