Thoughts? I got an offer today for a Proof Research barrel chambered in 6.5Creedmor, and it sounds too good to pass up. I just don't know the truth behind these barrels. One side of the table says they cool faster while the other side says they feel cooler because the heat it trapped in the metal that's wrapped by the carbon fiber.

Great hunting barrel...not so good if wanting to shoot it regularly. My gunsmith has done a few and speaks highly of them as a one/two shot deal.

Great caliber at least

The carbon wrapped barrels are great for having a thick barrel that acts like a heavy target barrel without the weight. They generally shoot very well. The main negative I see is the heat dissipating off the barrel after a few rounds. When looking through the scope, this heat comes off as barrel mirage and will heavily distort the target image when looking through the scope.

Also, the barrels are more stiff, and they do not show the large barrel harmonic swings as a standard barrel does when testing loads. For example, when testing loads, a standard barrel will have an open group, string a group, and then find the sweet spot load that tightens up and shoots good. You can see some groups open up.

When testing loads with a carbon wrapped barrel, even the groups that are out of the accuracy node still shoot decent. On a standard barrel, the loads that shoot bad, or out of the accuracy node, will open up more than the carbon wrapped barrels. I've noticed this with the multiple carbon barrels, like Proof and Christensen Arms barrels.

I think the carbon wrapped barrels are great for a hunting rifle when you will be firing few rounds at a time to heat the barrel up. If you plan to use it as a target barrel and plan to put multiple rounds down it in a short period, the barrel mirage you see in the scope will become an issue very quickly.

Modulus of elasticity, the ability to flex back to it's original position is what give the composite wrapped barrels an edge in overall consistence. But as you pointed out it does have drawbacks. They don't dissipate heat like a metal barrel in fact they hold heat due to it's insulation properties. Metal barrels flex and there nothing you can do about it other than allow for it. With composite barrels their nature/modulus of elasticity tends to pull them back to zero. Any composite has to have some kind of a binder to hold the fibers or matting into place and this is their biggest weakness since heat plays hell on the binding material. Many years ago we developed a pulltruded fiberglass sucker rod for oil wells. Do to the weight saving as opposed to steel we could run larger pumps down hole, move more fluid with smaller pumpjacks than a steel string would require. All went well until I went out to California and installed a few wells in the Elk Hills area around Bakersfield. Due to thermal activity down-hole temps were reaching almost 400 degree's and was playing hell on the adhesives used in the standard rod causing them to break down. The same thing happens to composite barrels if over heated and they completely lose the modulus property of zero. With that said it will take an extended amount of shooting to raise the kind of heat needed. Pay as much attention to the outside of the barrel as you do the inside and it will help in keeping a barrel from pulling off zero. Metal when heated expands and you want that expansion to be consistent. With a few thousands difference from one side to the other in wall thickness will cause it to expand unevenly and push to the thicker side which heats just a little slower. This is one of the reasons I don't like fluted barrels, there's far to much room for inconsistency.

I thought carbon wrapping on barrels was done 2 ways. One being actually wrapped around the barrel in a circular pattern and the other ways being laid along the length of the barrel? Different properties to the different methods.

I have seen different opinions regarding the stiffness of carbon compared to all steel barrels. In order to obtain the same stiffness as steel doesn't the barrel have to be wrapped to such a large size that the weight vs size begins to have diminishing returns?

Off topic for one statement. I remember back in the 80's when fiber rods were introduced in pumping wells, but I was under the impression the advantage was in non corrosive material and the lighter weight allowing for less pump jack size and reduced energy costs to lift a barrel of liquid. I never realized it allowed a larger pump? (Plus the USA was having to import drill pipe from Japan and cost of steel had skyrocketed)

Back to topic, if you get carbon barrel to be stiff enough what will you have to do to stock to accommodate the larger diameter? Please give a followup if you do install carbon barrel.

Most use a biaxial weave or matting, fiberglass rods were pulltruded in one continuous strand with no matting. This gave them a tensile strength comparable to steel. With less weight hanging off the horses head allows you to lift more, offering the ability to run a larger pump. That is if you don't scale down your equipment at the surface.

Also a little longer stoke in the pump form the yoyo effect of the fiberglass rods.

That is true, you get an extra 9 inches per thousand ft. Best way to describe it is using a rubber band and a weight, get the harmonics right and you get a longer stroke down-hole than at the surface.