why are barrels octagonal?

[Rifleman1776]

The latest issue of American Rifleman has a article about the gunmakers at Colonial Williamsburg. The article reads more like a paid commercial but is still interesting. One comment made was new to me. It stated rifle barrels were made octagonal to designate the bore was rifled. I had never heard this before. On reflection, I believe original smoothbores I have seen were round and original rifles were octagonal. But, is this really the history of the shape?

 

[8 BORE]

Its earier to mount a sight on a flat than a round

 

[Crewdawg445]

I have found the profile was strictly for aesthetic purposes and served no function besides that. Hopefully Dave can elaborate if he comes across this. The Gunsmith of Colonial Williamsburg mentions this as does a few sources I have. At work so I don't have access to my literature on the bench.

 

[Crewdawg445]

Its earier to mount a sight on a flat than a round

That has nothing to do with it, soldering is much easier than cutting a dovetail slot along with making and fitting the piece.

 

[George]

It stated rifle barrels were made octagonal to designate the bore was rifled.

There were original guns, both rifled and smooth, which were octagon to round, and smooth rifles with barrels all octagon.

Sounds like another myth in the making.

Spence

 

[Crewdawg445]

There were original guns, both rifled and smooth, which were octagon to round, and smooth rifles with barrels all octagon.

Sounds like another myth in the making.

Spence

Exactly, I can see all the "speculations" in-work...



Straight from the mouth of the man himself at 3:15.

 

[Black Hand]

It stated rifle barrels were made octagonal to designate the bore was rifled. I had never heard this before. On reflection, I believe original smoothbores I have seen were round and original rifles were octagonal. But, is this really the history of the shape?

Then how does one explain the octagon to round barrels on tradeguns (smoothbore) and the Harper's Ferry (Rifle). This sounds like a statement made by an uninformed person who is pulling misinformation from a place where the sun doesn't shine...

 

[dave61965]

On speculation here but maybe it’s because of the actual forging process of manufacturing the barrel, I know from being around steel mills and large forging facilities the hammered blanks are octagonal after they come off the forging hammer to be machined later, just a guess.

 

[Black Hand]

On speculation here but maybe it’s because of the actual forging process of manufacturing the barrel, I know from being around steel mills and large forging facilities the hammered blanks are octagonal after they come off the forging hammer to be machined later, just a guess.

But when barrels were created by hand-forging in the period, they were shaped around a round mandrel from a flat bar of iron that was forge-welded to create a tube. This yields a round barrel initially...

Modern barrels that are bored could conceivably be any shape.

 

[Straekat]

Let's not forget this idea comes from Gussler, who also has opinions on the subject of powder horns being attached to hunting bags. ( Leaving that there for whatever it's worth. )

 

[brayhaven]

Good question. I’m inclined to think it was style and tradition. Most (orig) rifles have oct. and most smooth and shotguns I’ve seen have round or partially round barrels. Though most military rifles had round.
I looked a little in Greener’s book “The Gun and it’s development”. He Has a lot of info on barrel making from the very earliest hand cannon to cartridge guns. But nothing on reasons for shape, I could see. Octagon allows for more stiffness for the same weight barrel, which might allow less harmonics in a rifle.

 

[Crewdawg445]

On speculation here but maybe it’s because of the actual forging process of manufacturing the barrel, I know from being around steel mills and large forging facilities the hammered blanks are octagonal after they come off the forging hammer to be machined later, just a guess.

Barrels of the day were forged welded over a swage block with a round mandrel in the center, they then were filed to shape later.

 

[Artificer]

Exactly, I can see all the "speculations" in-work...



Straight from the mouth of the man himself at 3:15.

I'm paraphrasing but it sounded like "there was no practical reason for the octagon shape, but rather a matter of style...."

Good Grief, Folks, that movie was made in 1969 and intended for audiences who knew almost nothing of making a Flintlock Rifle in the Period. It was never intended as a "do all, end all, chiseled in all stone for all time" testament on period guns or gunsmithing. A whole lot has been learned of the period since 1969 and Colonial Williamsburg has updated what was told to visitors during the years many times since my first visit in 1975.

Yes, I have found "bum scoop" being passed at CW by some folks at CW over the years, but please tell me anywhere on earth that bum scoop hasn't been passed either through ignorance or sometimes people who can't explain things well?

How many people here remember a time when shotgun barrels almost universally were made ROUND, but when they first introduced
"flat ribs" onto the tops of the barrels to improve sighting for Trap, Skeet and finally hunting barrels? I have no documentation to prove that
was part of the reason period rifle barrels were made octagonal with flats on the top, but I'm sure they realized it improved sighting.

Gus

 

[TFoley]

I've often wondered why they were not hexagonal, since a hexagon shape is far easier to calculate than an octagon.

 

[Crewdawg445]

I'm paraphrasing but it sounded like "there was no practical reason for the octagon shape, but rather a matter of style...."

Good Grief, Folks, that movie was made in 1969 and intended for audiences who knew almost nothing of making a Flintlock Rifle in the Period. It was never intended as a "do all, end all, chiseled in all stone for all time" testament on period guns or gunsmithing. A whole lot has been learned of the period since 1969 and Colonial Williamsburg has updated what was told to visitors during the years many times since my first visit in 1975.

Yes, I have found "bum scoop" being passed at CW by some folks at CW over the years, but please tell me anywhere on earth that bum scoop hasn't been passed either through ignorance or sometimes people who can't explain things well?

How many people here remember a time when shotgun barrels almost universally were made ROUND, but when they first introduced
"flat ribs" onto the tops of the barrels to improve sighting for Trap, Skeet and finally hunting barrels? I have no documentation to prove that
was part of the reason period rifle barrels were made octagonal with flats on the top, but I'm sure they realized it improved sighting.

Gus

My basis is speculation isn't proof which there is a vast amount of "speculation" around here on ALLOT of topics. My references stem from that video, which old but is one of the finer examples that exist and a small passage I found which I'll post up when I get home later this evening. I believe there also is a reference of this on the American Pioneer Video series which highlights the process of forging a barrel. In short, my response was strictly based upon the amount of speculation which again IMO isn't definitive proof. I personally feel two forms of reference isn't all that convincing, however if the octagon profile was of great importance in some matter that likely would have been documented from builder to builder. In the end though, all we may have is a basis for some speculation!

 

[Artificer]

I very much agree that the more period sources, the better.

A couple years ago were discussing a very early 19th century Manual for Military Riflemen and even though the Manual was entirely documented and had been regarded as "chiseled in stone" for years, it had some really bad bum scoop in it. During the discussion or later, it came out somewhat accidentally and thanks to the internet, that the American author had to have plagiarized a slightly earlier British Manual and the weird stuff was not in the British Manual.

There are also plenty of types of original documentation that contain legends/myths/bum scoop that began before or during the period that are still regarded highly by many today, even though sometimes the legends/myths/bum scoop were disproved IN THE PERIOD, as well as later.

Gus

 

[Carbon 6]

Why did rifles of the civil war era have round barrels, but lever guns ten years later had octagon barrels ?
If there is a reason I doubt it has anything to do with rifling.

 

[Rifleman1776]

Sounds like another myth in the making.

Thanks for all the replies. I believe what Spence said sums it up quite well. I'm not a fan of CW. I think it is a place more of commercialization than historical reference. e.g. the same AR article said they are going to charge tourists $95.00 to fire five rounds from a flintlock musket. Our one visit (and last ever, I promise), we paid for the full show. Got in and found all the shops closed. Paid for nothing. It's a rip, IMHO.

 

[Black Jaque Janaviac]

One reason for octagon profile that I have not seen suggested is that it could help keep the barrel locked in place during the rifling process. Go to 10:00 in the video, you'll see Mr. Gussler clamping the barrel to prepare to cut the rifling. If you imagine the torque that is applied to the barrel during the rifling, you can imagine that clamping to a flat surface will help.

In Gussler's video he has a rifling guide with 7 grooves. However, it is possible that a guide could be made with 1 groove, and instead of rotating the guide, the maker could rotate the barrel, producing 8 groove rifling.

 

[Coot]

I've often wondered why they were not hexagonal, since a hexagon shape is far easier to calculate than an octagon.

A hexagonal barrel would be heavier than either a octagon or round barrel of the same caliber.