from 1960-1965 winchester sold the model 59 ultralight semi auto shotgun (hey, they are now 59 years old!)-- it had an ultra thin steel barrel wrapped in fiberglass/epoxy--its downfall was 3 fold--1st was that is was so light it was hard to shoot as it had considerable muzzle flip, 2nd was the myth that the barrels would blow up because they were just fiberglass, 3rd was that the aluminum receivers often cracked just behind the bolt handle from heavy loads--you can still buy them today, and if the receiver is not cracked you can still safely shoot them
I would bet that the steel liner in a CF barrel would be enough steel alone to be safe ( just look at the kimber 300wsm mtn ascent-- those tiny 7/16" threaded muzzles haven't split yet-- the CF makes them lighter and add stiffness to the ultra thin barrels and dampen the harmonic whip of steel--some manufactures claim they have heat dissipating properties, I'm not totally convinced of that sine both CF and most epoxies are actually insulators (though if manufactured correctly they can be conductors)