Octagonal Barrels

[bluelake]

I wasn't exactly sure where to put this, so...

What is the reasoning for octagonal barrels on many bp arms?  Is there something structural about it, such as withstanding gas pressures, or was it more ornamental?

[Three Hawks]

I wasn't exactly sure where to put this, so...

What is the reasoning for octagonal barrels on many bp arms?  Is there something structural about it, such as withstanding gas pressures, or was it more ornamental?

Now that is a really good question.   It's one of those questions that is so good, it never occurred to me before.   I have no idea why so many barrels are octagonal.  But I'll bet someone who has will be along pretty quick with a reasonable answer.

Three Hawks

[bluelake]

It's because squares are easier to forge then rounds.  An octagon is a square with the corners "knocked down"

How did they do it?  Did they take a solid square bar, knock down the corners and then drill it out?  Did they take a sheet, bend, forge, and then take down the corners?  Some other way?  It's interesting, as it was done like that here in Asia, too (and the sides of the octagon are perfectly straight and flat).

[bluelake]

Thanks!  

[cb]

Here's a link to how it's still done by some in the time honored fashion ...

Solid steel drilled barrels first appeared in the 1830's, but rifle barrels retained the octagon shape until the early 1900's.

[Gambia]

Most octangle barrels are for rifles and are s/b it was for added strength .they were first forged as a damascus barrell arround a  mandrill then their  flat faces were formed on a large grindstone simular to those used by the Sheffield knife makers, the early ones were hand powered and then it changed to steam.Another thing was the rifling of the barrel it was easy to rifle a flat sided barrel all you did was once you made your first groove or land you then turned the barrel onto the next flat and cut the next groove this was in the time of the long hand opperated  rifling machine.
Another interesting thing about barrel grinders and also knife grinders when steam driven became the thing the average life span of a grinder was just over 40 years it was a dirty job
Feltwad
A Flint Lock will not secure a chicken house door

[Captchee]

Dang  , all the good answers are taken . Well that’s what I get I guess for working late .

As I understand it  the octagon does 3 things
1) if provides  for a more rigid barrel  while at the same time allowing the barrel  material to be somewhat soft .
 Normally if you measure from a flat to the  bore  and then from the  peak to the bore , you  will find about .025  or more  in diameter

2) ease of welding . As steve mention , barrels were hammered by hand , around a mandrel  somewhat smaller then bore size . As such the barrels are somewhat round  as the anvil “ hope that’s the right name “ that is  use has half round  notches in it . If you get muzzleloader , you will see , if I recall Hershel House  forge welding up a barrel using the half round anvels  .. The barrel is then hammered , Not ground  to a to a  given wall  thickness .
Rotated , hammered again , so on and so forth . then the  flats are draw filed or ground  to true them up .
 later as feltwad stated , this changed to just making the barrels thicker and grinding the flats , not drawing thiem

3) as steve said again . It  provides for a easy way to know the barrel is true .
 Now that should not be confused with meaning that the bore is true . We are only speaking of the outside of the barrel

  Now with the bore , special reamers are made  to bring the bore to a given constant , clean bore size . Then the barrel is placed in a rifling machine.
 If you go to the  the link for Toad hall , given above , you will see  examples of a rifling machine

 This is where what feltwad said comes into play ..
 Later when steam and water  hammers and grinders came into play , the processes changed a lot . But it was  not really a whole lot  easier to produce a  octagon barrel , then a round one. but a minsat had been  instilled and people  wanted what they had come to know as a proper made barrel  

 Now I was also once told , long ago  by  a learned foe, that  it was much simpler then that .  In his view the octagon was architectural   IE #1
 Basically people  looked for strenght  in nature .
 Basically a true round was weak ,  and it was thought that   if a tree would bend  and sway in the wind ,  a round barrel would do the same .
 Yet a bee’s honey comb is ridged , withstands many times its own weight upon its walls , without deforming   as such , this was felt to be the best design for  something like a barrel .
 Now true or not . I cant say . There sure seems to be a lot of examples of round barrels . However I can see the logic in that explanation as well

[bluelake]

Wow, lots of great information!  Thanks, guys  

Ever since I bought my son a .32 cal. Remington rolling block with octagonal barrel (pre-1898) years ago, I always thought that style barrel looked really sharp.  Now I appreciate it even more and like it that much more.

[bluelake]

I just ordered Forging a Flintlock Rifle Barrel by Jon and Chris Laubach

Has anyone seen it?

[Kermit]

"Octagonalizing" stuff is pretty old.

I've done more than my share of traditional wood boat work, necessarily including sparmaking and oar making. It's pretty easy to get a hunk of stuff--wood in this case--to a square condition using hand tools. Then on the way to getting round stock, you knock the corners off (and there are clever formulas and jigs for marking out the lines for this, even on tapered stock) to get it eight-sided. From there it's pretty simple to eyeball it into a sixteen sided state, and from there to round.

You'll see a lot of stuff--oars and spars--that never get beyond octagonal. Oar looms are a common example in traditional boats.

I'd guess that stopping at octagonal when you are using files to do the work is not much more than a way to save a bunch of really fussy work. Getting wooden spars to the eight sided state is quick and simple. It's from there to round that takes time--and skill--and might have been seen as just guilding a lily. And then folks probably just liked it, thought it was the way it was supposed to be, and never thought about it much after that.

But I've been wrong before...

[Three Hawks]

I, too have made more than a few spars. Getting a true octagon from a true square is not at all difficult.   From octagon to sixteen and sixteen to thirty two sides requires skill and a trained eye.   Masts, booms, yards, sweeps and oars are far too large for lathes and must be done by hand. (Except in the case of factory made oars and extruded alumin(i)um spars which are blasphemous in the extreme and to be avoided as if diseased as they are truly the handiwork of Satan.)

Fortunately, wood suited to masts, booms, and yards is very easily worked by hand, and pleasant work it is, too.

Three Hawks

[Gambia]

Thee Hawks; How big a mast do you need ?The Grays Harbour Historical Seaport can mill a log 122 Ft. long and up to 40 inches in diameter.They have the largest lathe of this type in North America. Check out their website.I visited the shop a couple years ago and was IMPRESSED.I grew up around the shipyards  on Georgian Bay in the 30s but I never saw anything to compare.

[Kermit]

I worked out of a logging camp on the Olympic Penninsula and have been around the Lady Washington and GHHS since before she was launched. Having a "lathe" that big is fairly easy. Getting timber that size out of the rainforest and TO the shop is the challenge--never mind just finding spar quality that size!

[Riley/MN]

I've been noticing some of the new power poles put in here lately... Sure look like wooden masts to me!

[Gambia]

The Hoquiam City watershed is the source for most of the logs the Seaport uses.Its close to town and readily accessible.There  are plenty of 100+ year old fir in the watershed.For many years the City had a policy of cutting on a very long cycle.Sadly I believe that has been changed [for money reasons] to a much shorter cycle.