TRYBE Defense Match Series AR-15 .300 AAC Blackout Threaded Barrel 7.5 in Balance Profile 1/5 Twist 5/8x24 Black Nitride TRB-15B35P7NGQ-5R-NP3. By speeding up the twist rate to 1:5 from common 300 BLK rates of 1:7 and 1:8 these Faxon Match Series...