Ballistic Advantage Premium Black Series 16" .308 Win Barrel, BA Hanson Profile w/ Lo-Pro Gas Block, Mid Length. This .308 Win chambered 16" barrel is machined from 416R stainless steel with a QPQ corrosion-resistant finish. This BA Hanson Profile barrel includes a pinned low-profile gas block and a gas block retaining pin. This Premium Black Series barrel showcases a 1:8 twist rate, 5/8" x 24 TPI, and a 1.03" Gas Block Seat.