I believe if you do the math you will discover that the inertial loading that Roger calculated is the smallest component of the force acting upon the barrel. Rogers calculations are simply nothing more than the rotational inertial force due to the spinning of the bullets mass. It is in reality a trivial thing. If you do the math I believe that you will find that the largest force vector is the axial thrust. As I stated in a previous post this is given by:

bullet mass X bullet accel X cos helix angle.

This force wants to wind up the barrel due to the helix angle created by the rifling twist. The tighter the twist the greater the axial thrust. Therefore, since most of the fluted barrel guns are small bores with fast twist barrels I think you will find that for a given barrel weight the fluting is better from a torsional stiffness stand point. Put another way:

If you are limited to a 4 pound barrel that is to be 26 inches long. A fluted section will in fact provide the stiffest section. I do not know of any clearer way to say it than I just did. It is a mass versus stiffness relationship!

I can calculate torsional stiffness if you like it is not a difficult proposition. I see little reason to do so as most here will simply disbelieve the truth because it disagrees with their preception of what is best. That behavior is best described as close minded! An I-beam is not torsionally stiff either. Aren't there any Civil or Structural Engineers around here to disspell that misconception.

I agree with you that in most barrels the extrusion (not engraving, engraving involves the cutting of material) of the bullet is reacted against by a nonfluted barrel section.

Todd E

Doesn't anybody care that fluting is butt-ugly? I don't need theory, calculus, algebra OR a gun rag to tell me that!

What looks cool is to peer down an old English double rifle and see that the barrel twist are opposite each other. NEAT!

Yes. I agree.

" Rogers calculations are simply nothing more than the rotational inertial force due to the spinning of the bullets mass."

F=MA or in this case Torque = Moment * Angular acceleration.

"It is in reality a trivial thing."

Yep.

"If you do the math I believe that you will find that the largest force vector is the axial thrust."

No argument

" As I stated in a previous post this is given by:

bullet mass X bullet accel X cos helix angle.

This force wants to wind up the barrel due to the helix angle created by the rifling twist."

No. this is true only so long as the bullet is being accelerated in an angular fashion. If you were to stick a bullet in a 1:1 twist barrel and pressurise the barrel there would be no torque created so long as the bullet did not move. There WOULD, however, be quite a bit of linear thrust developed.

" The tighter the twist the greater the axial thrust."

Again, only because of the enrgy required to accelerated the bullet rotationaly.

" Therefore, since most of the fluted barrel guns are small bores with fast twist barrels I think you will find that for a given barrel weight the fluting is better from a torsional stiffness stand point."

The torsional load is still of such small consequence that spiral fluting will lose more logitudinal stiffness than will be gained by resisting (or over resisting) the small torque generated.

" Put another way:
If you are limited to a 4 pound barrel that is to be 26 inches long. A fluted section will in fact provide the stiffest section."

Possibly, if it's doene right and not spiral fluted, or fluted with a flute on top and bottom (as opposed to a rib on top and bottom) And the side flutes really do not add a whole lot to the solution. But we are starting to reapproach the I-Beam section here.

" I do not know of any clearer way to say it than I just did. It is a mass versus stiffness relationship!"

I understand, and I agree with your thinking, just not all of your conclusions.

"I can calculate torsional stiffness if you like it is not a difficult proposition. I see little reason to do so as most here will simply disbelieve the truth because it disagrees with their preception of what is best. That behavior is best described as close minded!"

Agreed

" An I-beam is not torsionally stiff either."

No, but it is tortionaly stiff enough for such a small reaction. which is my point.

"Aren't there any Civil"

LOL. We gonna build a road?

"or Structural Engineers around here to disspell that misconception."

Now this I've done.

"I agree with you that in most barrels the extrusion (not engraving, engraving involves the cutting of material) of the bullet is reacted against by a nonfluted barrel section."

I've alsoi worked in the Wire and Cable industry and am WELL familiar with extrusion, both plastic and metallic. There is very little extrusion taking place in firearms, and that that does take place is limited almost fully to axial loading. The most extreme curret form is in the 22-17 aliber Swager where a 22 rimfire is fired in a specially chambered 17 caliber barrel. Even the man who "accidently" rechambered the 6.5 Arisaka to 30-06 without increasing the bore only remarked on the MUCH increased axial reaction, with no mention of increased torque.

None of the above takes work hardenning into consideration, and there may be some rational there.

[This message has been edited by John Y Cannuck (edited 04-22-2002).]

Here is the equation for torsional stiffness

theta = [torque X length] / G X J

G = Modulus of Rigidity and is material specific. Steel (all steels) G=11.5E6 psi. Irregardless of hardness!

J = polar second moment of area. This is a function of the cross section.

If I have a barrel with a round cross section with a OD of 1.200" and a bore of .308" with no lengthwise taper the torsional stiffness will be 10,990 lb/deg

If I take the same exact barrel and cut six flutes into the OD that that are semicircular with a radius of 0.075" the torsional stiffness of the fluted barrel is
10,090 lbs/deg.

The difference is approximately 9%. The mass savings is approximatley 5.5%. The position of the flutes is not important.

Vibe,
As long as you have a rifle there will be both axial thrust and radial loads applied to the barrel, which are trying to unwind the barrel due to the barrel's rifling. If this is not occuring then your bullet has stripped out or the rifling in your barrel is gone. Your 1:1 rifling scenario would provide a rifling rate of 1 twist per inch. This would induce massive thrust and radial forces on the barrel. You must understand that the bullet wants to go straight. We are acting upon the bullet with the rifling to induce a stabilizing spin. This is Newton's 3rd Law. This is why rifle barrels oscillate. I cannot see what is so difficult with this entire concept it is very straight forward.

It is sad that our engineers are so ignorant of the basics of mechanics that they would argue such a simplistic mechanics problem. Prehaps this explains why there are so many product recalls and plain stupid designs being produced in this country.

I agree with the guy that said fluting is butt ugly! I AGREE 100%. I use fluting solely for function (which is to reduce weight while maintaining some stiffness). The functional rifle need not be a thing of beauty it sole purpose being to perform.

Todd E

You waste your time and energy. Go on to greater pursuits and let Todde think what he wants.

I am afraid that you must be correct in you conclusion. The 1:1 twist scenario was SO oversimplified that he had to have INTENTIONALY missed the point that the bullet was held immobile in that example, Once you screw up the constraints that severly the rest is just garbage. Oh well...you can lead a lack-ass to water....

Reading Todds opinion of engineers doesn't surprise me much. But it does lend some insight into why LEOs are as a whole now held in such high esteem (Attn. Sarcasm warning).

On the other hand I knew this product was in the works. But was not aware that it was available commercialy yet.

http://www.clarkcustomguns.com/stabilizer.htm

http://www.clarkcustomguns.com/gbs1.htm

Vibe,
How long have you been a practicing mechanical engineer? Longer than Roger I hope. Do you suppose the Clark Custom Gun guys have done any order tracking to understand the vibrational characteristics of the Mini 14 or just thrown an adjustable mass damper on like the Browning and USRAC did?

Todd E

Since 1986. And I worked as a design drafter for 5 years prior to that.

I'd become aware of the impending patent of this particular device several years ago.

http://www.vni.com/books/appstudies/rifle/rifle3.html

I only just now discovered that it has been put to commercial use. I guess it was a test of the "worst case scenario" that it's been put on the Mini-14 since it has such a poor reputation for accuracy.

Browning basicly stole the idea for the BOSS from existing benchrest practices. BOSS style tuners had been in use for several years before Browning "patented" it. I do not think the folks at Clark invented this device either, but they are working with the inventor to market it. which is a lot more honest than what Browning did.

This device is a LONG way from just a "repackaged" BOSS. It works on a completely different principle. Even the QUE wasn't really a "repackaged" BOSS. Although Browning lawyers did manage to "prove" that it was. The QUE patent was on the attachment system, which WAS unique. Browning still stole that one too. The only simularity of the system from Clark is that the attachment system, like the QUE system' does not requre the barrel to be threaded. But that's about where the simularity ends.

[This message has been edited by Vibe (edited 04-22-2002).]

I was always going to buy one and try it but never did.

Chic

I really don't remember where it was built, though I'm thinking I saw something a few weeks ago that made me think it's still available, just under the Browning patent now.

Check here

http://www.queindustries.com/

QUE Industries
PO Box 2471
Everett, WA 98204

"I remember seeing an item that you could attach to your barrel with a special heat activated epoxy and it worked in a similar fashion to the BOSS."

Heat activated? Yes. Epoxy? No. This was the really neat part, the attachment method used a heat shrinking metalic band to fix it to the barrel. You did have to send them the dimension of your barrel at the location yoou wanted to mount it though. And before Todd reams me on this, I argued till I was blue in the face and was finaly proved wrong about how "No metal SHRINKS when it gets hot" Well this one does. The drawback was that once installed, this band usually had to be cut off to remove the tuner/brake.

"I was always going to buy one and try it but never did."

Yep. Me too. I liked the looks a lot better than the looks of the BOSS.

[This message has been edited by Vibe (edited 04-22-2002).]

Could you explain how the Clark Custom systems works. I did not get much out of their website. They talk alot and say nothing! What frequency is this system tuned for? How do we know that this frequency is in fact the excitation frequency? How much energy does it take to get a barrel to resonant anyway?

Todd E

Probably not as well as the Three Rivers Tech/ PV-Wave site does. But that site explained it enough to where I understood how it works. You're smarter than I am so it should be no problem.

"I did not get much out of their website."

Really? How strange.

"They talk alot and say nothing!"

"What frequency is this system tuned for?"
If you bothered to read the whole study then on page 4

>http://www.vni.com/books/appstudies/rifle/rifle4.html

you would have read this.

>The most significant realization should be small, tight bullet groups across a range of loads and temperatures (which affects internal ballistics), with no adjustments required on the part of the shooter. <

Indicating that this is a dynamicly self tuning system.

"How do we know that this frequency is in fact the excitation frequency?"

Subsequent verification testing exihibited by the before and after testing. SOP stuff. Duh!

" How much energy does it take to get a barrel to resonant anyway?"

These values seemed to have worked for the inventor.

>The simulator consistently uses the cgs metric system of units, and the magnitude of the impulse was 10 dyne/cm applied over 1-mesh intervals for 0.1 msec. <

Why don't you get yourself educated by a nonpartial entity and stop believing all the BS posted on websites. The website is an advertisement and it is all about marketing. Wise up man!

They gave you an impulse, which is the input excitation. They provided a wavelength, but no Eigenvalues. This is less than half assed BS. The data on their website sounds like they are trying to explain a modal analysis, but don't know what one is so their explanation is very poor and obviously full of BS.

Todd E

quote:

---

Originally posted by Vibe:
Roger

I am afraid that you must be correct in you conclusion. The 1:1 twist scenario was SO oversimplified that he had to have INTENTIONALY missed the point that the bullet was held immobile in that example, Once you screw up the constraints that severly the rest is just garbage. Oh well...you can lead a lack-ass to water....

Reading Todds opinion of engineers doesn't surprise me much. But it does lend some insight into why LEOs are as a whole now held in such high esteem (Attn. Sarcasm warning).

On the other hand I knew this product was in the works. But was not aware that it was available commercialy yet.

http://www.clarkcustomguns.com/stabilizer.htm

http://www.clarkcustomguns.com/gbs1.htm

---

By 1:1 twist did you mean 1 turn in 1" or no twist at all? In any case it moves us into fantasy land.

Clark has simply hung extra mass on the end of a barrel and justified it with a lot of sophistry. Barrel will not move less. Frequency of movement are dampened while duration and range of movement increase.

Dynamically tuned? Bound to sell

Wally

Don't know the formulae, or anthing else about it. I do understand the way it works. Have the bullet leave the end of the barrel when the velocity of the oscillation is at a minimum.

You guys all need to chill. This is not that important in the grand scheme of things.

The Savage M1910 semi auto pistol put in to compete with the Colt 1911 in the u.s. army trials used the twisting force to rotate the barrel out of lock with the slide. One related phenomenon is when I use heavy (330gr.) bullets in my .44mag. winchester 94 the 'scope rotates in the rings. It doesn't move backwards or forwards just gradually rotates anti clockwise!

The "I" beam analogy is not applicable as "I" beams are designed for load bearing applications to support heavy vertical loads smaller sideways loads but virtually no torsion loading. The ratio of expected loadings for vertical and horizontal is why the beam is of "I" section, deeper than it is wide.

To see if any of these fluting ideas have merit look at big guns, particularly tank guns and anti aircraft guns. The savings in mass that would result would be considerable and highly beneficial to mounting weight, traverse speed and recoil management. But the only fluting you see is straight, deep flutes intended for barrel cooling.

The only other plan of going away from the plain cylindrical form is to go to an ovular form with the large dia. in the vertical plain, but this is just to resist drooping due to gravity. As you can imagine the machining problems of producing this form are considerable.

I still think spiral flutes (or any flutes), are ugly... well, except on "ugly" military and benchrest guns... then they're right at home!

I agree with you. Who the heck is Gary Larson by the way?

Todd E

Brad

I will state that if Shaw sez flutes is the best thing since sliced bread, then I know better than to even try'em...but then I never intended to flute a barrel, not my style.

------------------
Ray Atkinson

ray@atkinsonhunting.com
atkinsonhunting.com