PROOF Research PR15 PXT 6mm ARC 18" Carbon Fiber Barrel

Eighteen inches is the sweet spot for 6mm ARC in an AR-15. You get most of the velocity the cartridge has to give without turning the rifle into a 20" gun, and the rifle plus one gas system runs a long, gentle pressure curve that suits a semi auto shooting for score.

PROOF wraps a match grade core in carbon fiber, so this barrel weighs about what a pencil profile does while staying as stiff as a heavy one. It also dumps heat far faster than steel alone, which shows up on the fifth and sixth shot of a stage rather than the first. PXT rifling ramps the twist up gradually from the breech, reducing engraving force and stretching the useful life of the throat.