PGW barrel fluting, more than just looks?

Shabazz

Shabazz

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I was reading a review on the PGW Timberwolf by Gunmart in the U.K and came across this very interesting part about the barrel fluting.

"Starting out with the 26” barrel, the external spiral fluting is very noticeable, tactile and rotates in the opposite direction to the inner rifling to allegedly improve barrel harmonics and is certainly a trademark visual feature."

I have never heard of barrel fluting being used to influence harmonics, and honestly I find the idea pretty fascinating. Unfortunately the reviewer doesn't say who made this claim, so I figured I would post here to get your thoughts and hopefully PGW's if they happen to see this post. I would have put this in their forum but it doesn't seem to get much traffic.

Just to be clear this isn't meant to be sarcastic or anything, I'm genuinely curious.

Link to the article: http://www.gunmart.net/gun_review/pgw_timberwolf
 
Changes in structure will change the way vibration will move through the metal, so I guess it's possible. Never heard of it phrased that way before though. Slightly larger cooling surface, and stiffer for a given diameter have been proven , have to see what comes of this, should be some testing done to verify. - dan
 
dan belisle said:
Changes in structure will change the way vibration will move through the metal, so I guess it's possible. Never heard of it phrased that way before though. Slightly larger cooling surface, and stiffer for a given diameter have been proven , have to see what comes of this, should be some testing done to verify. - dan
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Are there any sources online showing that proof? I had read somewhere that removing material can't possibly make a barrel stiffer, it made sense to me but if it's been tested I'd be very interested to see it.
 
It does nothing that any other fluting doesn't do.... Also.... More material means more rigid...


Edit... Correction, it does one thing.... Add manufacturing costs
 
A fluted barrel will be more rigid than a non fluted barrel of the same weight.

The same way that in structural applications a tube will be stronger than a rod of the same weight.
 
I think the question here is whether the helical spiral which is in the opposite rotating direction as the rifling improves the shooting harmonics. If you consider a bullet spinning down the barrel, the bullet will have friction against the barrel. Since the bullet is spinning, a frictional torque is applied to the inside of the barrel in the direction of the bullets spin. So the argument is now if the helical rifling pattern can offer an asymetrical resistance to torque. In english, can we design a fluting pattern such that barrel is harder to twist in one direction than the other? If you've studied mechanics of materials, torque resistance is dependent on the distribution of material away from the center. But this quantity is not dependant on the radial positioning of mass around the center. Therefore, in the static sense, this asymetric rifling pattern probably does very little.

Now if we consider the actual vibrations and motion of the barrel, well the math here becomes full retard. Furthermore, the vibrations of the barrel depend on so many dam things, that again, it becomes difficult to solve this situation in an FEA program. So in practical terms, gun makers have created very accurate rifles with many other types of rifling patterns. Considering that all very accurate rifles all have 1) good barrel, 2) good stock, 3) good bedding/chases system, 4) varied fluting patterns, I'm inclined to think the rifling pattern on these rifles does very little to effect accuracy.
 
6MT said:
Me thinks Jerry is an unbeleiver.
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One thing I noticed is that the fluting helps brake up its patterning for camouflage purposes. Some times the front of my barrel disappears in the grass xD

Other than that, I knew about the rigidity, but now I'm curious regarding the harmonics theory! Need to find a way to test it.
 
The rigidity of a material is dependent upon E*I. E being the Young's Modulus of that substance and I being the "second moment of area" (basically a shape factor). The second moment of area basically accounts for mass further from the bending axis having a greater degree of impact upon the rigidity. And that is why we design steel I beams and hollow tubes instead of solid beams and rods. Yes, if you filled in the hollow spaces with material you would have an even more stiff structure, but at a much higher weight.

So fluting for a certain degree of stiffness for less weight. Yes.

Now the spiral opposing the torque imposed by the spin of the bullet... I think the theory hold merit on a theoretical level (for the very same reason of rigidity)... But you'd actually have to have the fluting spiral in the same direction of the rifling. I'll post a picture of my rifle as a visual aid to try to walk through the logic. (And because it's damn ###y).

So, the bullet comes out with a right hand spin. Meaning the top of the bullet is moving to the right as you look towards the target. So, looking at the muzzle, (as in the beautiful picture), it's turning counter-clockwise. To induce that spin, there is an equal and opposite force exerted on the barrel. Therefore, looking at the barrel it would be like holding the muzzle and twisting it clockwise. Thus making the spirals "tighter". Now to complete the thought experiment, imagine removing all the material which doesn't have the greatest "second moment of area" (I)... all the stuff with the least radius. You would be left with a spiral of metal like a spring. And it would be "easy" to turn clockwise, and "hard" to turn counter-clockwise.

For those of you still following.... the score is. Yes, more rigid to bending. Not more rigid to torsion... in fact, maybe less rigid.

But, diminishing returns here. Less rigid to torsion means that as the bullet fires there is a tendency for the rifling the "straighten out"... so your 1 in 10 twist might become 1 in 10.00000000001 (I just typed a lot of zeroes and didn't do the actual calculation, it's small). How soft your bullet jacket is actually plays a role, and probably has a greater affect on consistency than the barrel would anyways since bullet jacket material may be slightly different for each bullet.

Conclusion: The spiral aspect of the barrel fluting having anything to do with consistency is a stretch... Looking damn fine, which is half the battle after all... well... here's the picture.

 
The comparison isn't removing material. It's between a fluted barrel and a non-fluted barrel of equal weight. The fluted barrel will have more material farther away from the axis, making it stronger in torsion and bending. That equal weight part, is really important in this, otherwise removing material equals removing strength.
 
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