Let's Talk Carbon Barrels... What are the REAL advantages and disadvantages?

[Rent Outdoor Gear]

The carbon barrel seems like a natural evolution on a long range hunting rifle and selling point almost anyone would see as an advantage.

Theoretically, you get the stiffness of a heavy contour rifle barrel, improved resistance to heat walking, and a much lighter firearm?

I would like to hear some real world experience with them

1. Are they as accurate as a regular custom barrel?
2. I assume they start as a custom, high-grade barrel cut down significantly and then built up with carbon/glass/epoxy resin. Can somebody (MIKE) chime in here to tell me a little more about this?
3. Heavier rifles are known to be a more stable platform for long range shooting (just look across the line at any 1000 yard match). Obviously extremely heavy rifles are not practical (nor legal in some states - Idaho has a 14# limit as I recall). What are you giving up in accuracy with less mass weight and why? Is a carbon barrel the best of both worlds?

Appreciate anyone's experience here...

Thanks!

Coop

 

[HellsCanyon]

Oh this will get interesting in a hurry... First off, I've not shot very many carbon barrels, but I'm familiar with the methodology and how they work and what important factors you need to make them shoot good.

The two main problems historically with carbon barrels have been inconsistent accuracy (some carbon barrels shoot, others have not... from the same manufacturer!), and heat retention. Carbon fiber is NOT a very good conductor of heat (When compared to steel) thus you don't see any carbon fiber barrels in high round count competitions. There are certain blends of carbon fiber, graphite, resin that work to dissipate heat better, but they still are not on par with steel. Every company has their own 'blend' and methods which affects these properties.

Another issue mentioned is inconsistency. Due to certain manufacturer application methods, you will get tension or torque induced into the barrel during some phase of the carbon fiber application. This can greatly affects accuracy and makes the gun inconsistent and unpredictable. We've hopefully mitigated this issue with our first few carbon barrels and we are very close to getting a first few rifles built.

The benefits of CF and Graphite like you say is the same stiffness and rigidity that you get in an all steel barrel at a fraction of the weight. You get the same accuracy that you do out of a heavy contoured barrel without having to lug around the extra 3-5 lbs of barrel for it.

As far as heavier guns being more accurate or easier to shoot, here is my take and belief on it. Indeed it is harder for the average shooter to shoot a lightweight rifle accurately at distance, but that has a lot more to do with the shooter than it does the rifle. Historically "lightweight" rifles have had short sporter contour barrels (already a handicap right there), and sporter style stocks. It is a LOT harder to shoot those sporter style stocks with a very consistent cheekweld and to keep them steady in all conditions. They just aren't built for natural point of aim ergonomics... Also, up until recently, most "lightweight" stocks wouldn't fit anything over a #5 contour barrel. If you wanted to run a heavier barrel contour, you were stuck with a 35+ oz rifle stock which pretty much took your "lightweight" goal for the build out the window.

Now you can get a lightweight stock that will fit heavy contoured barrels and still fall into that 1.5lb-ish category and is ergonomically designed to allow a more naturally accurate shooting platform. Total game changer in my opinion... Add a 2.5 - 3 lb carbon barrel at 26-28" instead of the historical 5lb+ steel barrel and you're getting somewhere.

Mike

 

[Justin Crossley]

I copied this from another website. Thought it was worth reading. Kirby Allen knows a thing or two about custom rifles.


"I have fitted alot of carbon fiber barrels to custom rifles and have learned a few FACTS from my actual hands on testing. This is what I know:

If you take two barrels, for example, two #4 contour barrels, one carbon wrapped, one all steel, the all steel barrel will be dramatically stiffer. Also, the weight reduction on the wrapped barrel will not be much at all.

If you take two barrels, for example, 1.200" straight cylinder barrels,one carbon wrapped, one all steel, the all steel barrel will STILL be stiffer then the carbon wrapped barrel but in the comparision between these two large diameter barrels, the carbon wrapped barrel WILL BE much lighter in this application.

I know this because have taken barrels, chucked them up in the lathe by the shank just as they would be supported by the receiver, then hung 10 lb weights off the muzzle end and measured the flex in the barrels for comparision. In every case, all steel barrels had less flex then the carbon wrapped barrels.

Its true that carbon is stiffer then steel for a given WEIGHT. That is what gets left out of the advertisments. Let me explain further. If you take two rods that are 30" in lenght, both weighing 5 lbs. One all steel, the other all carbon fiber. The carbon fiber rod will be several TIMES larger in diameter then the all steel barrel and yes it will be slightly stiffer as well. Unfortunately, its not practical to wrap that amount of carbon fiber around a barrel sleeve. As such, the strength increase advertisment is simply FALSE in a rifle barrel application.

Now onto barrel weight.

AS mentioned, if your comparing two rifles with large contour barrels, the carbon fiber barrels will be DRAMATICALLY lighter but their barrels will not be stiffer.

IF your comparing sporterweight barrel contours, You can build an all steel barreled rifle that is only marginally heavier then any carbon fiber barreled rifle so application is critical to get the advantage out of these barrels.

Now lets talk about barrel life.

Yes its been proven that carbon fiber barrels cool faster then all steel barrels. It has also been proven that the barrel sleeves used in carbon fiber barrels also heat up faster!!!! So its a bit of give and take here. I would say for a high volumne varmint rifle you could see some benefit in barrel life but in my testing, even with large capacity, hyper performance long range rifles, the barrel life advantage is less then 15%.

Considering that a good quality carbon fiber barrel will cost easily twice what an all steel barrel will cost, in my opinion, its not worth it, especially for a big game rifle that will be fired much more deliberately with low volume shooting.

I have tested a couple ABS carbon wrapped barrels in my 338 Allen Magnum and put them through some torture tests along with two all steel barrels, one from Lilja and one from Krieger. The ABS barrels both used Rock barrel sleeves. The test was to fire five, 10 shot strings. Shooting was done by shooting 10 shots as fast as possible. Let the barrel cool to the point I could just hold my hand on the barrel, repeat with 10 more rapid fire shots and continue to repeat until 50 rounds were down the barrel.

I did this with all four barrels, two ABS, one Lilja, one Krieger. After the test all barrels were pulled, cleaned and inspected for throat erosion and heat cracking. In the end, The ABS barrels had roughly 8 thou less throat erosion(throat length) then the Lilja barrels but they were identical, within +/- 1 thou of the Krieger. Heat cracking appeared to be nearly identical in all barrels.

From this torture test it was clear that if you mistreated ANY barrel with a chambering like this, you would not be saved by a very high dollar barrel which is advertised to offer dramatically longer barrel accuracy life. Just not the trueth.

I have also tested a couple rifles shooting them as they should be, this time both were in 7mm Allen Magnum. One was a Lilja 1-9 4 groove, #8 contour, 30" fluted barrel, the other an ABS 30" 1-8.7, 5 groove, similiar contour to a #8 with Rock sleeve.

Both rifles were shot and cleaned regularly, never more then three shot strings. Noticable accuracy drop off started at around 850 rounds with the Lilja, around 925 rounds with the ABS so yes, the ABS offers longer accuracy life but this is I am sure simply due to the different hardness of steel used in the cut rifled barrel compared to the much softer steel used in the button pulled Lilja.

Still, 75 more rounds for over twice the cost of the barrel was not worth it in my opinion.

I believe the ABS barrels are the very best barrels out there for a carbon wrapped barrel. They do shoot very well, in some applications they do offer significant rifle weight reduction but if used in the wrong application, they really do not offer much over an all steel barrel.

Just my findings."
__________________
Kirby Allen

 

[Rent Outdoor Gear]

Interesting read. I have read a lot of Kirby's stuff and studied his work. He's extremely thorough as you can see... Who the hell else would run 100 rounds through a 338 Allen mag in a day and purposely abuse a couple high dollar barrels?!?!! For those that don't know, the 338 Allen mag is a .408 Chey Tac necked down to 338. It's the baddest 338 wildcat that I'm aware of. I don't know how much powder goes in one of those cases, but I think they measure it in pounds instead of grains.

 

[tater]

Obviously extremely heavy rifles are not practical (nor legal in some states - Idaho has a 14# limit as I recall).

I don't quite understand a weight limit on a hunting rifle? I get bullet weight/KE minimums for certain game but a rifle's physical weight?
From what i've seen of Aaron he should be forced to carry a 30# rifle just to make it a little more fair

 

[realunlucky]

Very interesting thanks for posting that

 

[Rent Outdoor Gear]

I would be really interested to see how they do the lay up on barrels. I worked on the Hoyt carbon risers so I understand how critical layup direction can be. Carbon fiber is incredibly strong in tension so if you can orient the material so the structural requirements of your design - be it a barrel, bow, or airplane wing, are supported by the carbon in tension rather than shear or compression you'll get the most bang for your buck. I would assume they would use longitudinal and bias wrap at 45 degrees on a barrel. Maybe some other less steep also to closely match the twist pitch to counteract the uncoiling reaction at the shot.

DC

 

[Rent Outdoor Gear]

I don't quite understand a weight limit on a hunting rifle? I get bullet weight/KE minimums for certain game but a rifle's physical weight?
From what i've seen of Aaron he should be forced to carry a 30# rifle just to make it a little more fair

Idaho is pretty old-school with a lot of our hunting laws. We JUST got it passed to allow over 65% let-off bows a couple years ago. Mechanical broadheads are still a no-no and we can't use lighted nocks. Oh yeah, and your gun can't weigh over 14 pounds. That one is peculiar, but I'm sure it has to do with not wanting guys using a 50 cal across canyons. That's why we just have mike build us a 338 that weighs 13.9 pounds or 7 pounds if you like

 

[tater]

A 7 pound 338? Uh, gee thanks.
Shades of shooting my Pops' Rem 760 30-06 with a steel butt plate and 200 gr. handloads stuffed to the max when i was a little kid.
Nose bleeds and scope-brow.
Nope, if i'm feeling the need for 338 mag love my 9.5 pound No.1 will do.

 

[Rent Outdoor Gear]

A 7 pound 338? Uh, gee thanks.
Shades of shooting my Pops' Rem 760 30-06 with a steel butt plate and 200 gr. handloads stuffed to the max when i was a little kid.
Nose bleeds and scope-brow.
Nope, if i'm feeling the need for 338 mag love my 9.5 pound No.1 will do.

Tater - that's hillarious! I had the EXACT same experience!!! So picture this, I'm 12 years old, 102 pounds soaking wet. I put a half dozen rounds through this 760 pump and my ole' man is like what's a matter you puss!?! I looked at him (with tears welling up in my eyes) and muttered, "You shoot this F-ing thing!" First time I ever cussed in front of my parents in my life! He looks at me, sits down behind it and he put one round through it and said, "This piece of sh*t's going back to the pawn shop!"

Thank god it did! I think a 7 pound 338+ would need to come with a mandatory muzzle brake.

 

[tater]

Yup. One of those 'character building' things i guess.
I had bench rested pretty well everything up to and including a .460 Weatherby within a couple of years of shooting that nasty b**ch gun though.
I have found few things as obnoxious that thing was (except for hippies and my brother in-law).

It's kinda funny that your Pops had you be the guinea pig first though! That's a total old-time dad kind of thing to do.

 

[Rent Outdoor Gear]

A lightweight 338 with a brake would be tolerable - and gotta remember, it's a hunting rifle so you wouldn't be putting that many rounds down the tube. For hunting big-steep country the lightweight package is certainly appealing to me.


DC

 

[HellsCanyon]

We're waiting on barrels to build a few lightweight 338 Norma mags. Uses about the same powder charge as a 300 ultra but can hit 2800 fps with 300 grain bullets out of a 28" tube. With a good brake it really shouldn't be too bad. Most efficient 338 chamber out there and was specifically developed around a 26" barrel... Plus you can load them out of a standard long action without being limited with seating depth!

Mike

 

[Rent Outdoor Gear]

We're waiting on barrels to build a few lightweight 338 Norma mags. Uses about the same powder charge as a 300 ultra but can hit 2800 fps with 300 grain bullets out of a 28" tube. With a good brake it really shouldn't be too bad. Most efficient 338 chamber out there and was specifically developed around a 26" barrel... Plus you can load them out of a standard long action without being limited with seating depth!

Mike

That's critical especially when shoving a 300 grain pill (that's more like the whole precription) into the bore - if you're forced to seat them too deeply you eat up case capacity real quick!

DC

Coop

 

[HellsCanyon]

That's critical especially when shoving a 300 grain pill (that's more like the whole precription) into the bore - if you're forced to seat them too deeply you eat up case capacity real quick!

DC

Coop

Yep! We're real excited about these guns. Should be a wicked nice long range HAMMER! Run the ballistics through Shooter of that 300 grain bullet at 2800 fps and you'll see what I mean

Mike

 

[C.K]

You can push them faster than that if you need to with a 28" barrel. If you run the norma and the lapua at cip the noma will push a 300 grain faster. I feel the 300 NM is a better option out to a mile but after that the 338 NM takes over, and after that the big guns come out if I need to hit something with a lot of KE. It will be interesting on how your barrels turn out, another option would be a 5.5 contour and spiral flute it should be close in weight. As for muzzle brakes, yes your going to need a good one, fat bastard or a FTE if blow back bothers ya.

 

[Albino Rhino]

I would be really interested to see how they do the lay up on barrels. I worked on the Hoyt carbon risers so I understand how critical layup direction can be. Carbon fiber is incredibly strong in tension so if you can orient the material so the structural requirements of your design - be it a barrel, bow, or airplane wing, are supported by the carbon in tension rather than shear or compression you'll get the most bang for your buck. I would assume they would use longitudinal and bias wrap at 45 degrees on a barrel. Maybe some other less steep also to closely match the twist pitch to counteract the uncoiling reaction at the shot.

DC

Darin, you are absolutely right as to the fact that the lay up is critical. There are several different methods of laying carbon fiber to get what you need. For example, a 45 degree lay up is strictly used for torsional stiffness. An 89 degree is used for hoop strength and a shallow angle will help against barrel whip by increasing stiffness. Also, we have found that in a lightweight build they are more accurate than a standard stainless or cro-mo barrel. On our Kifaru Rambling Rifles we started with a Krieger #1 cro-mo 5R 20.75" in 308 and our best 3-shot groups were about 7/8" (2 overlapping holes and short flyer) in a rifle weighing 4# 14oz. We had an engineer who is a pretty big name in the military world (actually worked on Skunk Works) come in and work with our engineers to lighten up the barrel and increase stiffness. It is correct that a carbon barrel and a steel barrel of the same contour, the steel will be much stiffer. However a barrel of similar weight the carbon, assuming the layup is correct, will be much stiffer. Carbon is roughly 1/5 the weight but only (depending on type of fiber, and layup) can be much closer in strength than just 1/5. Thus giving it a much greater strength to weight ratio which is where the rumors come from. After we turned down and carbon wrapped our barrel we ended up with a lighter barrel that is capable of consistently shooting .5" groups (100yd) and Patrick Smith actually shot a 5/16" 3 shot group with factory match ammo.

Another rumor that's out there, thanks to some barrel manufacturers is their claim of thermal conductivity and heat dissipation using pitch fibers. It's true that pitch fibers have outstanding thermal properties however when laid in any manner other than perpendicular to the material needing to be cooled have the same effect as an insulator. the trade off is that if you somehow are able to lay fibers in a perpendicular manner you will be sacrificing strength. Also you need a place to transfer the heat. Heat does not just go away, it needs convection, it needs a place to go. Do not believe anyone telling you that carbon wrapped barrels actually dissipate heat faster than steel. The real weak link is the resin.

The true craftsmanship on carbon builds comes in dealing with heat expansion and contraction. Trying to get everything (steel, carbon, resin and harmonics) all happen in concert with each other is the trick because everything happens at different rates. On hunting rifles it's not a big issue but in a tactical scenario if you needed to lay down suppressive fire and maintain accuracy then it can be hard. There are resins that go up to 1000 F but still hold heat in the steel barrel and because carbon actually moves more at temperature you will see your shots walk. We actually wrapped a way to thin carbon barrel and shot it as fast as possible with a bolt gun and watched as the first 2 shots were tight then the following opened up to almost 5" and then after about 8 rounds the group started to tighten up again. Pretty funny behavior for a barrel to do, but damn, I love my job.

The way we have found to maintain accuracy is by a de-bulking process and proper lay up. We try to maximize hoop strength and barrel stiffness. It helps to use cut-rifled barrels that have been cryo-treated, nicely lapped (preferably after turning). Also, cro-mo barrels have a much greater hoop strength than stainless if you turn them down to minimum wall thickness. Especially in cold temps. Either one can be done safely with a proper safety factor. Another nice fact about carbon fiber is that it maintains it's strength in all temps. It is inert which is why NASA uses it in outer space.

So, yes, based on our experience, carbon wrapped barrels can be worth it depending what you are looking for. If weight is not an issue go steel. If you are trying to minimize weight while trying to maintain stiffness then go carbon. It's not just about cool factor or some pointless beauty layer on the outside of a barrel, it can actually perform a task. That's pretty much why the stuff exists. Carbon fiber is very neat stuff.

 

[robby denning]

I've only been around two of Christensen's Carbons. Both were adapted to Model 70 Winchesters, a 300 Win Mag and a 7mm Rem Mag.

1) Both guns shot sub MOA angles where before they were terrible (hence the barrel changes)
2) Shaved gun weight noticably
3) Ugly (but I used to think synthetic stocks were ugly, too, and I got over it)

 

[Rent Outdoor Gear]

Albino Rhino - EXCELLENT info! I was hoping we could get a carbon barrel expert to chime in here!

A couple points struck me as important in what you wrote:

1.) Carbon, in just about any layup configuration, is a poor conductor of heat and thus acts as an insulator to the steel core tube. Therefore, barrel cooling is not faster than a steel barrel because there is no direct route for heat to escape from the metal core to the outside edge where conductive and convective heat transfer take place to cool the barrel.

2.) Carbon and steel have different rates of expansion and contraction with temperature which may induce some unexpected effects and challenges to barrel makers and shooters in high volume shooting applications.

Is it safe to say that a carbon barrel may not be a great choice for high volume, rapid-fire shooting (tactical and perhaps varmint hunting like prairie dogs) because you may see more "heat walk" than a steel barrel and the steel core of a carbon barrel may be easier to overheat since heat transfer is not as good as steel barrels?

On the other hand, for a big game rifle, it seems carbon barrels are perfectly suited for creating a lightweight, accurate shooter with "heavy-rifle" accuracy without the heavy.

Appreciate your insights and thanks for chiming in!

Coop

 

[Albino Rhino]

Thanks, Darin. If you're ever in the Denver area cruise by the shop sometime.

Pardon me if Im away from the forum for a while. I'm at the hospital waiting for my wife to push this kid out.