Thread: carbon wrapped barrels

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