What's the consensus on carbon fiber barrels?

[1168]

This is news to me, and probably everyone else reading this read.

I thought that initially, but I think both are considerations that some people might weight differently. If I’m using a heavy profile barrel, its for precision reasons; if I’m using a medium profile barrel, its partly for heat, and partly for performance. If I’m using a pencil, its because I’m lazy. I’ve been curious about carbon wrap barrels for some time, and I might try one on a bolt one day.

Do carbon wrapped AR barrels tension/pull traction on the underlying steel?

[okie]

This is news to me, and probably everyone else reading this read.

I'm not saying it doesn't matter, I'm just saying that a pencil barrel can shoot sub MOA with a cold bore. It's heat expansion from volume that kills AR accuracy, not lack of stiffness or any such thing.

[1168]

I'm not saying it doesn't matter, I'm just saying that a pencil barrel can shoot sub MOA with a cold bore. It's heat expansion from volume that kills AR accuracy, not lack of stiffness or any such thing.

I’ve been trending toward the idea that they aren’t optimal for repeatable precision and accuracy. It seems a little easier to work up a decent load or grab whatever’s on the shelf, and reach your accuracy goals, repeatably. A 3-shot group with 69gr FGMM, sure. Most any barrel can shoot that acceptably. But I’ve got an older Noveske stainless thats thicc and shoots anything pretty well.

My sample size has limits, and I don’t PRS or Benchrest, so I have to defer to the experts. But in my sampling, its been easier to get excellent results with a chubby barrel than a skinny one, at their extremes.

[DG23]

I get it's stiff, but stiffness isn't the limiting factor with ARs, or even most bolt actions, especially if they're floated. The main reason for a bull barrel isn't stiffness or harmonics or whatever but just to keep the bore cooler. I mean anyone who's shot a pencil barrel and a bull barrel can attest to how cool the bull barrel stays. And I get that the carbon wrapped barrel will be cool to the touch, but that doesn't mean that the metal under it is.

Not sure where you heard that crap but yes it IS for rigidity. The taking longer to heat up thing is an added bonus.

You can easily get a bull barrel just as hot as a skinny barrel - It just takes a little longer (and then a little longer to cool back down)

Why does the heavy barrel STILL not 'string' for squat once it is so hot you can cook bacon on it as compared to what a pencil barrel would do if heated up the same way???

[DG23]

I’ve been trending toward the idea that they aren’t optimal for repeatable precision and accuracy. It seems a little easier to work up a decent load or grab whatever’s on the shelf, and reach your accuracy goals, repeatably. A 3-shot group with 69gr FGMM, sure. Most any barrel can shoot that acceptably. But I’ve got an older Noveske stainless thats thicc and shoots anything pretty well.

My sample size has limits, and I don’t PRS or Benchrest, so I have to defer to the experts. But in my sampling, its been easier to get excellent results with a chubby barrel than a skinny one, at their extremes.

Stick with what you you know here brother because you would be correct...

[DG23]

Forum DT...

[HHollow]

I would like to see a comparison between carbon fiber barrels, and highly fluted barrels such as on the earliest AR10 rifles. The first several US made AR10s had highly fluted aluminum barrels with steel liners. One sploded during a full auto torture test. Only maybe one or two of the earliest guns still wears aluminum, the rest being retrofitted to all steel The Dutch made very 100% nice steel barrels for their AR10s that are crazy fluted. see pic. Resulted in the rifle weighing less that 7 lbs.

[lysander]

I would like to see a comparison between carbon fiber barrels, and highly fluted barrels such as on the earliest AR10 rifles. The first several US made AR10s had highly fluted aluminum barrels with steel liners. One sploded during a full auto torture test. Only maybe one or two of the earliest guns still wears aluminum, the rest being retrofitted to all steel The Dutch made very 100% nice steel barrels for their AR10s that are crazy fluted. see pic. Resulted in the rifle weighing less that 7 lbs.

1) It wasn't a full auto torture test, just the standard 6,000 round endurance test, and s/n 1002 let go at round number 5,564. S/n 1004 was being tested in other areas, and had fewer rounds through it.

2) Both test guns (s/n 1002 and 1004) had all steel barrels fitted before test resumed. But there were a lot of other, bigger, problems encountered, the gas tubes warped, the gas tube connections broke off, they fouled badly, to the point of ceasing to function after 500 rounds, the extractors broke, and they had a bad tendency to shoot holes in their own flash suppressor.

3) The AR-10 only weighed less than 7 pounds in the advertising, the lightest version was the aluminum barrel version that weighed 7.35 lbs when tested, empty, no magazine or sling. By 1960, it had gained a little weight and test weights were 8.80 lbs.

[HHollow]

...3) The AR-10 only weighed less than 7 pounds in the advertising, the lightest version was the aluminum barrel version that weighed 7.35 lbs when tested, empty, no magazine or sling. By 1960, it had gained a little weight and test weights were 8.80 lbs.

The earliest Dutch AR10 variant (Cuban) weighed less than 7 lbs empty and had an all-steel barrel. See press release below. I have verified this weight personally. The Cuban AR10 had the crazy fluted barrel (pic above), no bayonet lug, and a lighter bolt carrier. The later AR10 variants added weight and durability. The Portuguese variant, for example, had a much heavy barrel (un-fluted).

[okie]

Not sure where you heard that crap but yes it IS for rigidity. The taking longer to heat up thing is an added bonus.

You can easily get a bull barrel just as hot as a skinny barrel - It just takes a little longer (and then a little longer to cool back down)

Why does the heavy barrel STILL not 'string' for squat once it is so hot you can cook bacon on it as compared to what a pencil barrel would do if heated up the same way???

Any barrel will string when it gets hot enough to expand. As I said several times, thicker barrels take a lot longer to heat up, and they dissipate heat faster into the air due to having more surface area. A bull barrel has roughly twice the surface area as a pencil and roughly three times the mass.

From a cold bore, any profiles turned from the same blanks firing the same ammunition will shoot just about the same, but a lighter profile will start to wander within about five shots, whereas a thicker profile might take 20 shots before it gets hot enough to start expanding. The difference between a heavy and light profile AR barrel isn't really relevant to the platform or the way its used, from a rigidity perspective. The whole platform has all kinds of other issues. It's not a precision rifle. You have a barrel slopped into an aluminum receiver and a bolt that doesn't stay square to the chamber when the cartridge is pressurized. Worrying about rigidity in an AR barrel at the expense of thermal mass and heat dissipation is like worrying about the effect of aerodynamics on the acceleration of a minivan.