Magnum Research Barrel, 22LR, 16.5 Carbon Weave Barrel, Black, 1/2 x 28 Threaded Muzzle, For all Ruger 10/22 Takedown Models RTBAR16GT The patented uni-directional graphite carbon fiber construction dissipates heat" so the barrel stays up to 43% cooler than steel barrels in a standard 500-round/20 minute test" with no change in zero