Proof Research's barrels exemplifies relentless pursuit of excellence. Whatever your preference is, you can expect the finest rifle barrel in the industry.The Carbon Fiber barrel features a full-profile, match-grade 416R stainless steel barrel blanks that are made in Proof's firearms division. The blanks are then turned down to a significantly reduced profile greatly reducing weight. This reduced contour barrel is then wrapped with high-strength, aerospace-grade carbon fiber impregnated with a proprietary matrix resin developed by an advanced composites division, PROOF Research ACD. The carbon fibers have a unique ability to diffuse heat and also moves heat very effectively through the wall of the barrel greatly increasing heat transport. The end result is an aerospace-grade, high-fiber content composite barrel that is stronger, lighter, as accurate as the finest precision steel barrel, and durable to perform in the most demanding environments. This 20" model is compatible with your 308 Winchester AR rifle.