I've seen these for 10/22's and even some magnum-caliber bolt guns.

Does anybody make them for AR's or is it just too hard to do -- with the gas hole and all.

I think it would be really cool with a CavArms lower and a (dare I say) Hesse or PO plastic upper.

Christiensen Arms (sp?) would make one on a custom basis. I asked them about it last year. I was told that they take your barrel and machine it down leaving the gas port area full diameter for the gas block. This would leave a carbon fiber wrapped area from the receiver to the gas block and then a second carbon fiber wrapped area after the block to the end of the barrel.It was very expensive. I like expensive toys, but it was too much for me to pursue it.

You might want to do a search on the web for the origins of the AR-10. The first ones had composite barrels...I still remember one of the pictures; the barrel had burst, and looked like a bamboo shoot that had been loaded with gunpowder...

That cured me of any desire for composites...