Bartlein Barrels introduces Carbon Fiber barrels!

[FrankG]

Frank, our approach is that we validate our process with the destructive assessment. Then once we trust the process, it’s just spot checks from there.

Because you guys single point cut, you do not add any residual stress to them in your process. So any residual stress would have to be there before you guys got the blanks. And since I’m sure you get them normalized, you should essentially have a barrel as that’s nearly stress free.

Really, only a cryogenic treatment to the blank would likely show a measurable reduction in residual stress. And that’s under lab conditions. I doubt one could see it on target except under severe abuse.

Correct in your statements.

Also to the cryo part and I've been saying this for 20 years. Cryo can help if there is residual stress in the blank. Again can help but it is not a guarantee. I also say it does nothing for accuracy and or help barrel life in anyway for the most part.

We've made barrels where we've taken half of the lot of material and had it cryo'd and we ran them thru the shop and would even split them up on customers orders per requests etc...

I remember one order for Al Warner (Warner Tool) for a half a dozen F class barrels in 7mm. Half the order was cryo'd blanks and the other half where not. All the same lot of steel. One of the barrels bowed so bad and the guy turning them asked me to look at it and asked my opinion on if it was o.k. or not. I looked down the bore and said, "Nope! It's junk! Make a new one!". I wouldn't send that blank to Al and Dan let alone anyone else. Guess what? It was one of the cryo'd blanks. Now that being said losing one or two blanks like this doesn't mean the whole lot is bad. One or two out of 2000 blanks is nothing per say.

I know Al reads this forum....Al don't be mad at me! LOL!

 

[FrankG]

Anyone that offers these for sale is just in it to sell you a solution looking for a problem. There is absolutely ZERO research or science behind carbon fiber wrapped barrels. I hope at some point someone sues them for all that they are worth because it is criminal to make such claims with ZERO science or engineering to back up their claims. Given the premium they demand for such things it ought to be considered theft. If I machine my wrench or ratchet body down and replace that steel mass with carbon fiber my wrench or ratchet does not work better for it's job and it is not more rigid, stiff or stronger. Their is a reason they do not make automotive pistons, camshafts, connecting rods, crankshafts, heads or blocks from carbon fiber let alone carbon fiber wrapped....LOL Looks like I will never buy a Bartlin barrel I just hope Brux, Krieger, Shilen and Douglas do not go there so I can keep buying great barrels from people that are not going to insult my intelligence for marketing nonsense.

You should clarify your post here. As I take it as a personal attack on myself and the shop. If I'm wrong than explain it.

Did you read my first post (#25)?

As far as I know the only two barrel makers that make regular post on this forum to my knowledge is Stan Taylor from Douglas Barrels and ourselves to share knowledge and to try and help everyone.

Things like this get me to the point of being done with the forums!

Regards, Frank
Bartlein Barrels

 

[FrankG]

I cannot attach a video to this forum at all. Or at least I don't know how. It's of a competitors cfw barrel and this was done by accident. If the cfw is stiffer than steel per say why does it vibrate/resonate more and or differently than a steel barrel of the same contour?

So off hand I don't agree that it is stiffer than steel.

If someone wants to see the video email me thru the shop and I can send it to you. It's a grainy video but it gets the point across.

Later, Frank

 

[Alex Wheeler]

Im glad to see it. A lot of guys like CF barrel for one reason or another, Im just glad to have this option now.

 

[FrankG]

I rebuilt this Browning Sako Safari that was originally a 243win. and did it in 260 Rem. for my wife.

It weighs 7.5# with out the scope. 9# with scope sling and ammo. It's an honest 1/2moa rifle. You couldn't pay me enough to sell this rifle and it's not even mine. Again it's the wifes. LOL!

Like I said you can change the contour to save weight etc..vs putting a cfw barrel on the gun and still have the gun shoot great. Again cfw barrels are not for everyone.

I like this rifle so much I used it last year for deer hunting and I'm left handed!

 

[rwj]

Anyone that offers these for sale is just in it to sell you a solution looking for a problem. There is absolutely ZERO research or science behind carbon fiber wrapped barrels. I hope at some point someone sues them for all that they are worth because it is criminal to make such claims with ZERO science or engineering to back up their claims. Given the premium they demand for such things it ought to be considered theft. If I machine my wrench or ratchet body down and replace that steel mass with carbon fiber my wrench or ratchet does not work better for it's job and it is not more rigid, stiff or stronger. Their is a reason they do not make automotive pistons, camshafts, connecting rods, crankshafts, heads or blocks from carbon fiber let alone carbon fiber wrapped....LOL Looks like I will never buy a Bartlin barrel I just hope Brux, Krieger, Shilen and Douglas do not go there so I can keep buying great barrels from people that are not going to insult my intelligence for marketing nonsense.

Each can choose to configure a firearm using whatever components they want. It is fantastic to have options! The ones that don’t work, and/or are too costly, eventually won’t sell and will disappear from the marketplace... capitalism at work!

 

[Hohn]

I cannot attach a video to this forum at all. Or at least I don't know how. It's of a competitors cfw barrel and this was done by accident. If the cfw is stiffer than steel per say why does it vibrate/resonate more and or differently than a steel barrel of the same contour?

So off hand I don't agree that it is stiffer than steel.

If someone wants to see the video email me thru the shop and I can send it to you. It's a grainy video but it gets the point across.

Later, Frank

CF is not stiffer than steel in an absolute sense. Those who make this claim are conflating stiffness (resistance to deflection) with *specific stiffness* (how stiff it is for its weight).

Moreover, the "high modulus" of carbon fiber that often appears on spec sheets is sometimes just for a single fiber. Under lab conditions. When you weave that fiber into a fabric, then impregnate with a resin, the properties of the resulting composite will vary a great deal with the kind of orientation and weave pattern of the fibers, and will be much less than the properties of a single fiber.

That is why the newer carbon fiber jetliners actually have the fibers wrapped around a particular mold, because the fiber orientation is *critical* to the overall structural properties of the composite.

The key takeaway here is that "carbon fiber" doesn't just have a single value for a stiffness or other properties, but a huge range that depends on which particular CF a person is considering. And those making statements of comparison might be tempted to cherry pick a particular value to suit their purposes.

A CFW barrel could be made stiffer than a steel barrel of comparable weight. But a CFW barrel of will not not be stiffer than a steel barrel of identical profile. If for no other reason, CF has poor stiffness in compression. And since a barrel that is oscillating will place one side in compression and the other in tension on an alternating basis with each cycle, the effective stiffness is limited by the compressive stiffness.

A compressive stiffness (as opposed to tensile) almost never shows up on spec sheets. Why? Too variable, too hard to to test.

 

[Straightshooter1]

A CFW barrel could be made stiffer than a steel barrel of comparable weight. But a CFW barrel of will not not be stiffer than a steel barrel of identical profile. If for no other reason, CF has poor stiffness in compression. And since a barrel that is oscillating will place one side in compression and the other in tension on an alternating basis with each cycle, the effective stiffness is limited by the compressive stiffness.

Yes, this is how I understand it. And I would add that I feel comfortable saying that a CFW barrel is "stronger" and a steel barrel since carbon fibers is about 10X "stronger" than steel.

The video kinda demonstrates it's strength:

 

[dcali]

You could make a carbon barrel stiffer than a steel one of the same profile. You just wouldn't want to pay for it.

 

[atblis]

Snip

A CFW barrel could be made stiffer than a steel barrel of comparable weight. But a CFW barrel of will not not be stiffer than a steel barrel of identical profile.
snip

I read this as that the current carbon fiber barrels are not as stiff. Supposing that's true, what would one need to do?

 

[dcali]

A brief lesson in composite materials:

They're called composites becasue they're composed of two components - in this case, carbon fibers and a "matrix", usually some sort of polymer that fills the gaps between the fibers and holds it all together.

Carbon fibers by themselves are very stiff and strong - more so than steel. The polymer matrix is not. It's very flexible and weak. The properties of the combination are somewhere in between.

Two things make a huge difference when it comes to strength and stiffness. One is the orientation of fibers. If you had fibers perfectly inline with the barrel, that would make for as stiffer barrel than if they were aligned at 90 degrees (in rings around the barrel). The second case would not be stiff at all - it would basically be the stiffness of the matrix, which again is very low.

The second factor is the percentage of the composite that is composed of fibers. The higher that is, the stiffer the overall material. In certain high end aerospace designs, you can really push this up to a high number and get some very stiff, light, strong materials. But it requires very careful manufacturing and is not easy. It would be prohibitively expensive to do for barrels.

Winding a barrel is just that- you wind the filaments around the barrel in a helix. This is easier to do, but the fibers are no longer aligned with the barrel and stiffness will suffer to the point where it's going to be less than that of steel. Winding also typically has a disadvantage of producing a lower percentage of fibers than a traditional hand lay up.

All of this is very general, and I don't know how the various barrel manufacturers do it- I assume they're wound, and a proof representative confirmed that to me a while back. I don't know what Bartlein does, but I would assume the same. That's not to say that you can't amke a good barrel by winding it. It's just that it will not be "stiffer than steel" in a static sense. It might vibrate faster, but that depends on a lot too.

There is a LOT more to composite manufacturing - it's a huge topic. This just scratches the surface.

 

[dcali]

Yes, this is how I understand it. And I would add that I feel comfortable saying that a CFW barrel is "stronger" and a steel barrel since carbon fibers is about 10X "stronger" than steel.

The video kinda demonstrates it's strength:

I wouldn't count on it. There are ways that composites can fail that steel can't. They're notoriously prone to impact damage (which is often invisible to the naked eye), for example, which can cause the fibers to separate from the matrix or (if it's a laminate) for layers to separate from each other. The "10x steel" numbers assume that it's 100% carbon and all aligned exactly with the loads. Neither is the case in reality. That said, they can be plenty strong, and strength isn't what drives a barrel design - it's not like we use them as levers.

 

[Straightshooter1]

A brief lesson in composite materials:

They're called composites becasue they're composed of two components - in this case, carbon fibers and a "matrix", usually some sort of polymer that fills the gaps between the fibers and holds it all together.

Carbon fibers by themselves are very stiff and strong - more so than steel. The polymer matrix is not. It's very flexible and weak. The properties of the combination are somewhere in between.

Two things make a huge difference when it comes to strength and stiffness. One is the orientation of fibers. If you had fibers perfectly inline with the barrel, that would make for as stiffer barrel than if they were aligned at 90 degrees (in rings around the barrel). The second case would not be stiff at all - it would basically be the stiffness of the matrix, which again is very low.

The second factor is the percentage of the composite that is composed of fibers. The higher that is, the stiffer the overall material. In certain high end aerospace designs, you can really push this up to a high number and get some very stiff, light, strong materials. But it requires very careful manufacturing and is not easy. It would be prohibitively expensive to do for barrels.

Winding a barrel is just that- you wind the filaments around the barrel in a helix. This is easier to do, but the fibers are no longer aligned with the barrel and stiffness will suffer to the point where it's going to be less than that of steel. Winding also typically has a disadvantage of producing a lower percentage of fibers than a traditional hand lay up.

All of this is very general, and I don't know how the various barrel manufacturers do it- I assume they're wound, and a proof representative confirmed that to me a while back. I don't know what Bartlein does, but I would assume the same. That's not to say that you can't amke a good barrel by winding it. It's just that it will not be "stiffer than steel" in a static sense. It might vibrate faster, but that depends on a lot too.

There is a LOT more to composite manufacturing - it's a huge topic. This just scratches the surface.

I'm no expert by any measure, but from what I've gleaned over the last few decades, you're right on for every point.

. . . including the 10X strength of steel issue as it being at 100% carbon.

Your input is great and a lot better said than I could have. Thanks for the time and effort.

 

[dcali]

I'm no expert by any measure, but from what I've gleaned over the last few decades, you're right on for every point.

. . . including the 10X strength of steel issue as it being at 100% carbon.

Your input is great and a lot better said than I could have. Thanks for the time and effort.

That video got me thinking. It’s impressive that there wasn’t more visible damage. That’s pretty much the worst thing you can do to a composite. But... this seems like the sort of thing where you could introduce flaws below the surface that you can’t see. Things like fibers separating or the composite, cracks in the matrix, or the whole composite separating from the steel. A small defect like that might not show up immediately, but it could be the sort of thing that grows slowly with every shot. One day, it’s not shooting like it used to and you assume it’s just shot out or there’s some other problem. You might never know that it was damaged.

That is *pure* speculation. But it’s the sort of thing that we checked carefully for in the aerospace industry - with techniques that aren’t available to shooters. It is a real problem. I’m just not sure if it manifests in barrels. I have no reason to think it does, but it wouldn’t surprise me. If I had a carbon wrapped barrel I would be gentle with it.

 

[atblis]

That 10x number is problematic. I wouldn't get too hung up on it as the answer. As mentioned above, CF is a rather anisotropic material. Steel is not. A barrel is both in compression and tension and that varies as it is oscillates.

 

[dcali]

And while I'm blathering on about composites, the other can of worms is heat. Typically, but not always, the matrix is an insulating material that doesn't conduct heat well. Carbon fibers are excellent conductors of heat. How this combination conducts heat away from the steel liner is a complicated question, but one worth asking. It would be easy to imagine that the thin liner builds up unwanted heat, being insulated by the matrix. An example of this from aerospace. We used to make laminated plates out of carbon fiber composites. The electrical guys needed to know how conductive they were for various reasons, so they did a simple test - measure the resistance from one edge to another, and from one side to the other (through the thickness). The electrical conductivity from edge to edge was very good - carbon is an excellent conductor of electricity. This was true even when the probes wouldn't have been touching the same fibers. But from face to face, there was no conductivity to be had -the matrix effectively insulated the fibers. It turns out that heat conduction and electrical conduction are similar, so this would apply to heat as well. Clearly, this is a complicated thing without a simple answer.

Proof swears up and down that they've solved this problem, but they haven't to my knowledge given a straight answer as to how. I believe the closest they came was to say that it the way they wound the fibers allows for lots of fiber to fiber contact, and a clean path for the heat to distribute all the way down the barrel, which is a good thing. I may have that slightly wrong, but that was the gist as I remember it.

 

[Hohn]

Yes, this is how I understand it. And I would add that I feel comfortable saying that a CFW barrel is "stronger" and a steel barrel since carbon fibers is about 10X "stronger" than steel.

The video kinda demonstrates it's strength:

Actually, that demonstrates impact toughness, and only the toughness of the resin matrix. In other words, they use a really good epoxy and properly cure it in an autoclave. Not sure what this proves, though. Would we expect a steel barrel to fail this test?

 

[Hohn]

Thanks Damon for your informed postings.

The thermal conductivity of carbon depends heavily on its form. Diamond is an excellent conductor of heat. Graphite, less so. Charcoal, pretty bad.


There's only one "ultimate" barrel wrapping material as far as I'm concerned, but nobody seems to be exploring Beryllium alloys. Beryllium has 300gpa modulus instead of 200gpa modulus of steel, has very high specific heat and good thermal conductivity. High specific stiffness, light weight, excellent thermal properties. Very little thermal expansion as it heats.

But I'm guessing the market for $4000 barrels is small.

https://materion.com/products/beryllium-products

 

[Hohn]

You could make a carbon barrel stiffer than a steel one of the same profile. You just wouldn't want to pay for it.

Yeah, you'd have to have all the fibers oriented axially and then do some "hoop" wraps of some sort for structural purposes. But it would have to be an overwhelmingly axial weave, and would be pretty fragile.

So what I meant wasn't that a CF barrel could never be stiffer than steel of the same profile, it's the that CFW as represented in the market never would be. (helical wraps).

 

[Straightshooter1]

Actually, that demonstrates impact toughness, and only the toughness of the resin matrix. In other words, they use a really good epoxy and properly cure it in an autoclave. Not sure what this proves, though. Would we expect a steel barrel to fail this test?

I would imagine if a steel barrel of the same weight had the same thing done in that video, you'd probably wind up with a crooked barrel. There is a way to find out!

You're right about the epoxy as it's a big factor in how a composite performs. And as far as I can tell, it's a major factor in how a CFW barrel can or can not dissipate heat well.