PROOF Research PR15 Carbon Fiber Barrel 16" 6mm ARC

PROOF's PR15 Carbon Fiber in 6mm ARC is the AR-15 barrel of choice when the build is a gas-gun PRS rifle, a 600-yard match gun, or any AR-15 trying to extract long-range performance from a small frame. Carbon fiber wrap over a 416R stainless match liner gives roughly half the weight of a comparable steel bull contour while improving heat dissipation, so the barrel does not walk through a 20-round stage the way a heavy steel profile drifts.

The 16-inch rifle-gas configuration is the sweet spot for 6mm ARC velocity without giving up handling. PROOF's CAMGAS port is sized specifically for this barrel length and caliber combination, which keeps the impulse soft and the extraction clean across the load window from 105-grain match bullets through heavier 108-grain ELDs. The 1:7.5 twist stabilizes the high-BC 6mm projectiles that make ARC worth running over 6.5 Grendel.

5/8-24 muzzle threads are PROOF's standard across the PR15 line, which is the right call for this barrel: it accepts any 6mm or .30-cal can or muzzle device without an adapter. Buyers expecting 1/2-28 should note this up front. The trade-off across the whole PR15 line is price and aftermarket gas-block fitment, the carbon wrap restricts certain low-profile gas-block clamping styles, so pin it or use a clamp-style block sized for the .750-inch journal.