Math, science, and barrel fluting

[epc308]

Too much time on a rainy day-
Over the years, there have been many claims regarding barrel flutes. Gun writers in the glossy magazines have regurgitated the same "facts" over and over, making claims of increased stiffness, weight reduction, and increased surface area to improve the cooling.
A recent thread in the Varminter and Hunting section of the forum about contour swerved to the subject of fluting. That made me sit down to pencil whip the whole thing.
I used a typical barrel contour for calculations. 1.200" D x 3" L cylindrical section at the breech, 23" straight taper to an .800" D muzzle, for an overall length of 26". The total surface area is 85.2 square inches.
Typically, flutes do not extend to either breech or muzzle, so I used 6 flutes, 20" long for calculations.
For ease of calculations, imagine the flutes are square on the end, rather than radiused.
I determined cross section of the flutes by using a square inscribed in a 5/16 round, which resulted in a flute width of .220, .045 deep.
To cut a flute, you remove existing surface area. That results in 4.4 sq"x 6 flutes=26.4 sq".
85.2-26.4=58.8
The area of each flute is 4.9, for a total of 29.4 sq"
58.8+29.4=88.2 sq", for an increase of 3 sq" of surface area.
Not exactly cooling fins.
Weight reduction? Using the same parameters as above, each flute reduces the weight by .04lb, for a total 6 flute reduction of .24lb.
Increased stiffness? You need a machine to do yield strength comparisons. For best results you need dimensionally identical barrels cut from the same stick of raw material to assure the same metallurgical makeup. Machine one with flutes, another without.
Push or pull to failure, calculate the results.
If anyone has empirical data for that, please share.
Any and all comments are welcome, but no fires, please and thank you.

 

[BenPerfected]

What about the looks of the barrel flutes to go with a nice action, scope and stock?... nice to have some bling
Ben

 

[BenPerfected]

 

[powderbrake]

The "increased stiffness" is compared to an unfluted round barrel of the same WEIGHT and length.

If you flute a barrel, it has less material, so it is less stiff than it was before fluting.

 

[jelenko]

Too much time on a rainy day-
Over the years, there have been many claims regarding barrel flutes. Gun writers in the glossy magazines have regurgitated the same "facts" over and over, making claims of increased stiffness, weight reduction, and increased surface area to improve the cooling.
A recent thread in the Varminter and Hunting section of the forum about contour swerved to the subject of fluting. That made me sit down to pencil whip the whole thing.
I used a typical barrel contour for calculations. 1.200" D x 3" L cylindrical section at the breech, 23" straight taper to an .800" D muzzle, for an overall length of 26". The total surface area is 85.2 square inches.
Typically, flutes do not extend to either breech or muzzle, so I used 6 flutes, 20" long for calculations.
For ease of calculations, imagine the flutes are square on the end, rather than radiused.
I determined cross section of the flutes by using a square inscribed in a 5/16 round, which resulted in a flute width of .220, .045 deep.
To cut a flute, you remove existing surface area. That results in 4.4 sq"x 6 flutes=26.4 sq".
85.2-26.4=58.8
The area of each flute is 4.9, for a total of 29.4 sq"
58.8+29.4=88.2 sq", for an increase of 3 sq" of surface area.
Not exactly cooling fins.
Weight reduction? Using the same parameters as above, each flute reduces the weight by .04lb, for a total 6 flute reduction of .24lb.
Increased stiffness? You need a machine to do yield strength comparisons. For best results you need dimensionally identical barrels cut from the same stick of raw material to assure the same metallurgical makeup. Machine one with flutes, another without.
Push or pull to failure, calculate the results.
If anyone has empirical data for that, please share.
Any and all comments are welcome, but no fires, please and thank you.

Yeah. Marketing and trade mags love the word 'improve'. Quantifying the 'improve' takes all the fun out.

 

[epc308]

What about the looks of the barrel flutes to go with a nice action, scope and stock?... nice to have some bling
Ben

I’m not disputing the bling factor. Some like metalflake paint on a composite stock, I like figured walnut. As the old saying goes- you pay your money and you make your choice.

 

[epc308]

Yeah. Marketing and trade mags love the word 'improve'. Quantifying the 'improve' takes all the fun out.

40+ years machining metal along with the KISS principal has made me swear by the concept of form follows function. Prove it’s better with math and science. Now there’s a novel idea...

 

[Kurz]

Old news and no reason to revisit the same flogged horse again.

We proofed these concepts 25 years ago with the same math and lab testing. We arrive at the same conclusions even way back then. You aren't adding anything new or startling, just more regurgitation.

 

[Dusty Stevens]

They look cool thats all anybody cares about in the end and all that matters to me if if a guy wants it or not.

 

[BenPerfected]

The "increased stiffness" is compared to an unfluted round barrel of the same WEIGHT and length.

If you flute a barrel, it has less material, so it is less stiff than it was before fluting.

Increased stiffness is a goal for some....

 

[joshb]

They look cool thats all anybody cares about in the end and all that matters to me if if a guy wants it or not.

Some day I’m going to get one of those “skip fluted” barrels. They just look cool!

 

[JSH]

Being involved in agriculture for a number of years and custom spraying, one individual could not plant a straight row if his life depended on it. Makes it tough to spray. His comment was he got more seeds in a crooked row than a straight one.
I find the concept of the two about the same.

 

[epc308]

Old news and no reason to revisit the same flogged horse again.

We proofed these concepts 25 years ago with the same math and lab testing. We arrive at the same conclusions even way back then. You aren't adding anything new or startling, just more regurgitation.

That's wonderful, but I hadn't/haven't seen said results before. As stated, I had time to kill on a rainy day. I had interest in the subject matter, and decided to share.
Shortly after joining and spending time reading the various parts of the forum, I told my wife Accurate Shooter can be like Facebook for rifle guys, with snarky comments that have no bearing on the subject matter.
You proved that today, sir.
Or, proofed, as you put it.
As with any social media, if you don't like what a person has to say, you can scroll on past.

 

[mike a]

Old barrels are less stiff.

 

[divingin]

Increased stiffness? You need a machine to do yield strength comparisons.

I can't see how fluting a barrel will increase stiffness. The material that remains was there in the original (non-fluted) barrel.

If you took a barrel, and created flutes by adding ribs, I could see stiffness increasing.

I could also see a claim of being stiffer than a barrel of equal weight.

I don't see the normal claim though. Then again, I'm not a materials engineer.

 

[DOGCAPPER]

Cooling is needed most at the breech end where no flutes are cut.
Bling seems to be leading the parade.

 

[Richard Coody]

The "increased stiffness" is compared to an unfluted round barrel of the same WEIGHT and length.

If you flute a barrel, it has less material, so it is less stiff than it was before fluting.

Exactly

The barrel was stiffer before fluting

 

[Ramblerman]

That's wonderful, but I hadn't/haven't seen said results before. As stated, I had time to kill on a rainy day. I had interest in the subject matter, and decided to share.
Shortly after joining and spending time reading the various parts of the forum, I told my wife Accurate Shooter can be like Facebook for rifle guys, with snarky comments that have no bearing on the subject matter.
You proved that today, sir.
Or, proofed, as you put it.
As with any social media, if you don't like what a person has to say, you can scroll on past.

Ahhhh the troll. You know what they say my man...those that don't understand it or just dismiss it will just try to tear it apart...kinda like the anti's and the 2nd Amendment, etc., etc.

You took the time to actually "show your work"...So I thought it added something and disagree that your beating a dead horse...maybe you are to the above "genius", but what that guy fails to realize is that not many here that actually read these posts have the experience they have... certainly not the knowledge that they gained 25 years ago....so it's too bad that person decided to disparage and not just "pass on by"...oh well, some folks are just not happy, nor ever will be.

 

[Kurz]

Shortly after joining and spending time reading the various parts of the forum, I told my wife Accurate Shooter can be like Facebook for rifle guys, with snarky comments that have no bearing on the subject matter.

These forums are populated by some of the best shooters and reloaders in the U.S. and some from Europe. Most of the best manufacturers contribute extremely useful information. Repetitive, redundant information is not useful.

Obviously I hit one of your nerves. Sorry about that!

What I wrote has every bit of bearing on what your initial post is about. Exactly as a matter of fact. Bruised feelings over not receiving the jumping for joy reactions and the pats on the back for math prowess is your problem.

This subject, as I stated, has been covered more times than most of us need to read again. You telling me that my 'snarky' comments have no bearing is just plain silly. And no I don't have to scroll by, ignoring this fact. Pointing this out is a way of trying to curtailing the next regurgitation for a few weeks anyway.

Have a great day!

 

[NZ_Fclass]

Anyone winning long range benchrest with a fluted barrel?