heavy octagonal barrels and accuracy

[stef76]

Just wondering if the heavy octagonal barrels in various offerings might have any inherent shot to shot accuracy advantage over regular lighter weight round barrels? Say for example a rossi 92 with octagonal vs round barrel?

[osteodoc08]

Longer heavier barrels are easier to steady for off hand shots, for me at least. There should not be any difference in practical accuracy with barrels of equal quality.

[fecmech]

I have 2 Rossi 92's in .357 caliber,a 20" round carbine and 24" octagon rifle. I can see no difference in mechanical accuracy between them. They are solid 3 moa 100 yd rifles that I have put thousands of trouble free rounds through. The extra weight of the octagon (About 1 lb. heavier) makes it "hang" a little better for offhand shooting and the lighter weight of the carbine makes it more pleasant to carry around. The carbine is also D&T'd for a scout scope mount under the front sight while the octagon is D&T'd for a tang sight. I would pick the configuration that appeals most to you and not worry about any accuracy differences.

[country gent]

The heavier barrels have slightly finer harmonics nodes than the lighter ones. Several things affect a barrels accuracy and consistency. Stress in the blank and or barrel when finished, this can cause a barrel to "walk" shots as it heats up. cross section of the barrel may have some effect and a octagon barrels thickness at the outside edges is going to more than the thickness of a round barrels.

[Bubba w/a 45/70]

For most purposes in this discussion, the stuff hanging off the barrel (magazine tube, hand guard, barrel band if equipped, ect.) will have much more of an effect than barrel harmonics for shot to shot accuracy.

From a purely theoretical point, the heavier the barrel the less tendency to wander with things attached to it.

The quality of the barrel, ammunition, and the correct combination thereof will be deciding factors.

Barrel harmonics have more play in the free float arena of target type guns....where the effects are more readily felt/found.

Also, the longer sight radius of a longer barrel will help with "accuracy" when shooting a levergun as much as anything else.

[indian joe]

For most purposes in this discussion, the stuff hanging off the barrel (magazine tube, hand guard, barrel band if equipped, ect.) will have much more of an effect than barrel harmonics for shot to shot accuracy.

From a purely theoretical point, the heavier the barrel the less tendency to wander with things attached to it.

The quality of the barrel, ammunition, and the correct combination thereof will be deciding factors.

Barrel harmonics have more play in the free float arena of target type guns....where the effects are more readily felt/found.

Also, the longer sight radius of a longer barrel will help with "accuracy" when shooting a levergun as much as anything else.

I had wanted to say "yes they do" in reply to this question but held back because I thought that was more wishful thinking on my part than reality, I like longer octagonal barrels, however I dont really think the normal options are heavier enough to make a difference - so I reckon Bubba has it here - the stuff hanging off the barrel is what counts (and how it hangs) plenty of long magazine rifles will walk up the target as they heat up - some dont - short magazine ones much less likely to do that - I have a 94 Oliver Winchester that stays on target - the front magazine hanger is not dovetailed into the barrel its setup as a recoil lug so the mag and barrel not tied together - I thought a manufacturing shortcut on Winchesters part but maybe not? Occasionally they do things right!

[Ballistics in Scotland]

I once knew someone who bought what looked like an extremely good heavy octagonal barrel blank from Numrich, in the days when it was a lot easier to get them out of the US. He shortened it, and found that the bore was considerably off-centre. After turning down, straightening and truing up round again, it was accurate - I don't remember in what, but maybe in something that didn't get very hot, as residual stresses can remain. As supplied, the groups would surely have walked as the barrel heated.

I like octagonal barrels too. But there is a chance that the same thing could happen, to a lesser extent than my friend's extreme example, if the barrel gets hot through grinding one flat at a time.

[indian joe]

I once knew someone who bought what looked like an extremely good heavy octagonal barrel blank from Numrich, in the days when it was a lot easier to get them out of the US. He shortened it, and found that the bore was considerably off-centre. After turning down, straightening and truing up round again, it was accurate - I don't remember in what, but maybe in something that didn't get very hot, as residual stresses can remain. As supplied, the groups would surely have walked as the barrel heated.

I like octagonal barrels too. But there is a chance that the same thing could happen, to a lesser extent than my friend's extreme example, if the barrel gets hot through grinding one flat at a time.

Its not just octagon barrels though - more a characteristic of long tube magazine rifles than of round or octagon barrel shaping.

[Drm50]

A few years ago I bought 38/55 Oct barrels from Numerich. After markets for 94 wins. When
cut they were all noticeably of center, and only 4" from Muzzel.

[yeahbub]

Just wondering if the heavy octagonal barrels in various offerings might have any inherent shot to shot accuracy advantage over regular lighter weight round barrels? Say for example a rossi 92 with octagonal vs round barrel?

.

Either can be made to work, but there may be some homework to bring it up to snuff. In my experience, the octagonal barrels have a slight accuracy advantage because they are left in their original external form after being drilled, reamed and rifled. Straight cylindrical barrels left at their original diameter are the same. Barrels that are lathe turned to the tapered external contour without being properly stress relieved can "spring", releasing unrelieved internal stresses where the most material is removed, hence, the bore being tight at the thick breech end and loose at the skinny muzzle. Properly stress-relieved barrels don't do this, but production costs being what they are, sometimes a batch of barrels may not have been left at temperature quite as long as they should have. In my experience, the octo barrels and cylindrical barrel blanks almost never exhibit this problem. When one of these "reverse taper bore" barrels shows up, it can generally be corrected with a bit of judicious pressure lapping with cast boolits. A case in point: I rebarreled a Marlin '94 in .44 Mag and test fired it when the barrel was still a heavy cylindrical blank. The naked unencumbered barrel shot all holes touching at 75 yards, and then I lathe cut the contour, gently, not wanting to hog off heavy cuts and get it hot or introduce new stresses. Once it was to size but before final assembly, I test-fired again and the groups with the same ammo were 2"+ at 75 yards. Slugging it revealed it was tight at the breech and looser at the muzzle by about .0002-.0003. I pressure-lapped it with 10-15rds of Crystolon 400 and finished with 5-6 of 600 (my standard approach). The taper was corrected, the bore smoothed and the accuracy had improved markedly but I don't remember precisely what the numbers were. After reassembly and hanging all those parts on the barrel, it will still put the Lee 200gr RNFP paper patched into 2" at 100, so I have no complaints.

[northmn]

I once knew someone who bought what looked like an extremely good heavy octagonal barrel blank from Numrich, in the days when it was a lot easier to get them out of the US. He shortened it, and found that the bore was considerably off-centre. After turning down, straightening and truing up round again, it was accurate - I don't remember in what, but maybe in something that didn't get very hot, as residual stresses can remain. As supplied, the groups would surely have walked as the barrel heated.

I like octagonal barrels too. But there is a chance that the same thing could happen, to a lesser extent than my friend's extreme example, if the barrel gets hot through grinding one flat at a time.

I built a couple of muzzle loaders using Numrich barrels when they offered ML barrels. They shot OK. Some said the only difference between a Numrich and a Douglas was 400 shots of wear in. When Douglas was the big name they offered a standard barrel and the premium. The difference was in run out at the breech. You were supposed to set the Douglas name on the barrel either up or down as they marked where the run out was. I had one that ran out on the edge of the octagon and the darn thing would work but hoot slightly to the left at 50 yards and slightly to the right at 100 for a good sight in (example) They recommended that a Douglas barrel be shortened from the breech and re-drilled for the breech plug due to run out. Later makers like Green Mountain would drill the blank then machine the flats to eliminate run out. They thought the harmonics were better if they machined the octagon and then drilled it. Over a 42 inch barrel run out was almost expected. Rifle barrel makers that did other wise and eliminated the run out proved that their system was a good for accuracy. They likely thought that for center fire barrels also.


Muzzle loading barrels were of relatively softer steel than centerfire smokeless barrels. The earlier cartridge barrels were also softer steel and many thought that the softer steel gave less vibration or tuning fork effect. Kind of thought I would throw this out. Octagon barrels were standard in muzzle loaders but I think they might have been that way for strength more than accuracy.


DP

[Ballistics in Scotland]

A few years ago I bought 38/55 Oct barrels from Numerich. After markets for 94 wins. When
cut they were all noticeably of center, and only 4" from Muzzel.

And true at the muzzle? That isn't a bend. That's a corner.

I think the most common practice with octagonal barrels is to drill and rifle the cylindrical barrel, and then reduce the outside to octagonal by grinding or milling. Memory is hazy after several decades, but I believe I was told that the Numrich barrel appeared to have been done with an industrial planning process. This I do not like for a straight octagon, which this was, and it is surely impossible for a tapered one, due to the impracticality of supporting the barrel against flexing on the far side.

The main advantage of turning a barrel to a round taper, is that you turn it on all sides every revolution, and heating can't but be equal on all sides. Grinding of milling to octagonal, the danger is of heating up one side more than the others. The best way would be to remove very small amounts of metal from all sides in turn. But we know how much that logic applies to production accountants nowadays, when it comes to rifling.

Still, plenty of octagonal barrels are true and accurate, and any deficiency in accuracy applies when hot, not for a first shot. People with high ambitions flute barrels, and that is surely at least as difficult to do well. The shape with the highest ratio of outside to inside is a circle, and at least in theory an octagon is better at shedding heat to the outside.

I think the main reason for octagonal muzzle-loader barrels was tradition, coming from the days when they were forged to that shape, and very limited lathe facilities were available. British long-range muzzle-loading target rifles were held closer, by the rules, to the military rifle than the very heavy American bench rifles, notably by a limitation on barrel weight. Octagonal barrels soon disappeared from that branch of the sport.

As to evenness of diameter along the barrel's length, I think that would matter a lot less if the muzzle-loader were for cloth-patched round ball.

[northmn]

I was merely mentioning what I ran into with ML barrels back when Numrich offered them. Douglas also made cartridge barrels and got out of muzzle loading type barrels. Barrels were made to copy fire arms made before the industrial revolution in the 1800's. Douglas did try to drill the barrels after forming them. There were others that milled them off centers to get the octagon. These are relatively modern makers. Todays machining is so far superior to even what was used when Numrich offered barrels it is unbelievable or when Winchester had octagon barrels.

Octagon barrels today are a novelty and a esthetic throwback to the days when they were more popular. One individual on another site made the comment that basically accuracy with a lever gun is based as much on the stuff it has to support as the barrel. We do not take a target rifle and hang a tubular magazine on it and put bands around the barrel to assist its accuracy. One individual in trying to find out how well his Winchester could shoot took off the magazine and fired it single shot. A lever action customizing shop prefers to convert them to rifles by removing the carbine barrel band system. As Ballistics in Scotland stated the first shot is usually good. A gunsmith friend I had would get paid to sight in 94 Winchesters. He would take several rifles to the bench, and only fire the 94's a couple of times and let the barrels cool to get the first shot on. Takes a bit of stress relieving of bands and stock to get a lever to shoot 5 shot groups at times. Some may do so out of boxes others not so much. I have a 35 Remington Marlin that hit dead on first shot or two and then would walk to the right until I worked over the forestock.


DEP

[marlinman93]

Heavy octagon or round barrels will hold their accuracy better as they heat up vs. lighter barrels. But how much better they hold depends on how much heavier they are. Guns I've owned with accurate lightweight barrels would begin to string shots vertically as the barrels got hot, and yet when cold they could shoot one hole groups.
I have some target rifles with barrels that are 1.25" round or octagon, and they will continue to hold accuracy better, even after getting pretty warm.

[yeahbub]

The way a few blacksmiths related the story to me was that the reason barrels were octagonal was that in the hammering and lengthening process (time consuming and labor intensive) it was easier to hammer out a square blank and then hammer the corners, forming an octagon of reasonably consistent dimensions making it easier to draw-file to final profile which was a matter of routine, whereas hammering out a consistant cylindrical diameter is difficult to do and essentially requires a lathe not all possessed. No lathe, no round barrels.

Something I read about barrel harmonics which agrees with northmn's comments on hardness and harmonics is that in the muzzleloading period, some makers happened upon a particularly soft and ductile iron which was easy to work and quick to make barrels with due to it being possible to use a drawknife to shave the octagon almost to final dimensions before filing. This malleability also translated to easier drilling and rifling, smoother finishes and accuracy untroubled by precise length characteristics or the location of escutcheons and other barrel attachments. I don't recall where this was, but I wonder if this iron wasn't an early form of Mehanite, a malleable iron still used today for its easy machining qualities and dimensional stability. IIRC, iron molds are generally made of Mehanite.

[GARD72977]

Did we come to a conclusion if octgon or round has an accuracy advantage.

Intresting that octagon was easier to produce 150 years ago and round is easier to produce today.

[Cosmic_Charlie]

Both mine and my son's Henry octagonal barrels in .357 shoot very well. Better than the two round barreled .44's I've owned, which were good shooters.

[brewer12345]

I notice that my octagonal barrel Rossi takes a lot longer to heat up than my Marlin round barrels. The Marlins are very accurate, but the heat up quickly and if you are doing target shooting you need to wait a while between groups or the heating up of the barrel makes POI move. The Rossi heats up more gradually and the change in POI is not nearly as noticeable. Of course, you pay for it with weight.

[bob208]

harry pope preferred round barrels. we know how they worked.
I have two under hammers target models. one with an octagon barrel the other with a round barrel. both are .45 and shoot great can not tell the difference.

[indian joe]

original question was heavy octagon vs lighter round barrel - that gets a yes to the octagon (or a yes to heavier?)