C=2PiR so diameter of 1.250" barrel= 99.74mm

Diamter of 3/16"=4.7625mm/2 R=2.318mm
C=2Pi(2.318mm)=14.96mm/2=7.48mm which is length of arc cut into barrel.

Across the top of the flute is the diameter = 4.7625mm

Total length of circumference of unfluted barrel= 99.74mm
Total length of the ten flutes 10(4.7625)=47.625mm

So:
Barrel 99.74
-Tops 47.625=52.12mm + (10x7.48mm arc)=127.62mm

Subtract the original barrel circumference of 99.74mm and this is an increase of 27.87mm in circumference, a little more than an inch.

Our barrel has effectively gone from a large 1.250" to a rather massive 1.60" and has lost weight at the same time. I do not see how this could weaken a barrel or cause it to flex more.

Did I make any errors?

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You are correct. Fluting of an barrel does not increase it's strength nor diameter. Fluting of a barrel would increase the circumference and therefore available surface area to allow faster cooling. The advantage of fluting, as I see it, is to provide additional stiffness when compared to a an unfluted barrel of the same weight.

For example, a 3/4" diameter unfluted barrel may weigh the same as a 1" diameter fluted barrel. The fluted barrel will be stiffer.

cwilson

A very good read.................

When people say fluting a barrel "stiffens" it, that is only true when it is compared to a thin barrel. Think of "adding" the steel necessary to create the raised portions on a thin barrel as if we welded them on. Then the "fluted barrel" is indeed "stiffer" than the original thin barrel. But it is not as stiff as if the entire OD was increased(non-fluted).

You just can't "stiffen" a pipe by removing portions of the metal from it.

Take 2 wood pencils(or a couple of 1/4" steel rods) and cut a flute 1/2 way through one of them perpendicular to the lead(across the pencil).

Blindfold yourself and have someone hand you one pencil(rod) at a time. Flex them and see which one is the "stiffest".

Good luck to you.

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Good hunting and clean 1-shot kills, Hot Core

quote:

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Originally posted by Hot Core:

You just can't "stiffen" a pipe by removing portions of the metal from it.

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I don't have any scientific or engineering data to back this up, but by fluting the barrel, aren't you essentially adding vaults - which would make make the barrel more resilient to directional stress?

It seems to me that an unfluted barrel would be easier to bend in half than a fluted barrel - just like an I beam would be harder to bend than solid steel.

You wouldn't change the elastic or conductive properties of the metal by fluting, but it does seem logical that you would increase both strength and surface area.

I don't know?

Interesting question.

Fluting is a compromise not a miracle.

Look under Articles Written by Dan Lilja and then Barrel Diameter and Fluting.

If you compare barrels by weight, then fluting makes a stiffer barrel. If you compare barrels by diameter, then the larger diameter barrel is stiffer. You cannot remove material and make a stiffer barrel. Kinda defies the laws of physics...

What I want to know, in terms of heat conductivity of metal, is how much "coolability" is actually gained by removing material? How much of the gain is offset?

DbBill is right, as usual.

And Rogers calculations still just relate to a diameter that would give the same effective surface area which would have nothing to do with stiffness.

Chic

[This message has been edited by Customstox (edited 03-15-2002).]

quote:

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Originally posted by dan belisle:
a greater surface area will cool faster than a small one of similar makeup and thickness. - Dan

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I was thinking about what sort of gain you would get from shaving a bull barrel down to increase its surface area. You'd be reducing its thickness at the same time. Wouldn't it heat up faster than it did before you fluted it?

Griff

The only reason that I can personally see to flute a barrel is to adjust the balance and handling if you feel it is to muzzle-heavy. When the gunsmith who built my Lazzeroni Patriot delivered it to me it had a balance point further forward than I had specified in the contract...I returned it and he fluted the barrel just enough to achieve the balance point specified. As an aside, I shot it before and after fluting and there wasn't any noticable difference in accuracy using the same loads.

quote:

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Originally posted by Roger Rothschild:
Kreiger lists on their site flutes 3/16" wide with 10 on a large barrel. I do not know how deep. For this I will assume they go 1/2 diameter deep.

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Wouldn't 1/2 diameter take you to the centerline of the bore, completely eliminating the barrel?

Example... A 1" diameter barrel, you cut flutes 1/2" deep, what's left?

Rob, perfect !!!!

It is a given that the barrel of the same weight as the fluted one would be stiffer. That wasn't even argued. But most of us have seen the reason for fluting as a method to increase the stiffness of a barrel and that is nonsense.

Chic

"This is a controversial topic. I'll try to sum-up fairly, but
I'll get flamed anyway.

1. The best argument for a fluted barrel is that it weighs less than a
barrel of the same profile, without sacrificing much stiffness. (An
argument cannot be made that a fluted barrel is STIFFER than a heavier
round barrel of the same size, as removing steel never made a cylinder
stronger. As for the argument that the fluted barrel is "stiffer" than
a thinner barrel of the same weight, see below.)

2. The second best argument is that fluting makes a rifle lighter without
a noticable, or only a negligible, decrease in accuracy.

3. The third best argument is that it cools faster. However, a heavier
barrel also heats-up slower, so that's your tradeoff.

4. It looks cool.

Arguments against fluting:

1. Fluting moves primary vibratory motion into more complex secondary,
tertiary etc. forms of harmonic motion. This is because the fluted
barrel is more likely to flex where it is not reinforced. Putting an odd
number of flutes on it just increases the complexity of the harmonics.

Since compensating for primary vibration is just a matter of finding a
happy node and sticking with it by loading to a certain velocity (found
by experimentation), it is the other harmonics that are the primary
cause of natural inaccuracy in an otherwise sound gun. This is covered
in detail in Harold Vaughn's recent tome, and I defer discussion to
that authority.

Referring back to Argument #1 FOR fluting, a thinner non-fluted barrel
of the same weight may have more primary harmonic motion. But, we know
how to compensate for that. It will probably have less secondary, tert.
etc. motion, as there is no assymetry in it to promote it. This means
that the thinner barrel can be load-compensated by loading to specific
velocities, and accuracy can be acheived.

It may, however, have relatively few velocities where it is highly
accurate, compared to a thicker barrel with slower primary harmonics.
This is why thinner barrels "like" fewer loads than thick barrels.

A thicker fluted barrel, having less barrel whip in the primary
harmonic, will shoot various loads to a smaller extreme spread of
dispersion. It will however, be more difficult to find loads that have a
greater precision accuracy, as loads that compensate for primary and
secondary harmonics will encounter greater and more complex tertiary and
quaternary harmonics, loads that compensate for primary and tertiary
harmonics will encounter greater secondary harmonics, etc.

So, we would find that a fluted heavy barrel may shoot OK with most
any load, but not fantastic with any one load.

2. If done improperly or the barrel is stressed by the operation, fluting
can cause uneven expansion when heated, increasing dispersion when
hot and therefore decreasing accuracy.

3. Engineers may laugh at you and then lead you through embarrasing
"thought experiments" that lead you to question your choice in barrels.

Ken.

PS My thanks to the structural engineer on the rec.guns
newsgroup who lead me through some thought experiments a few years ago. :^)"