Manufacturer: Palmetto State Armory (PSA) Model: PA-15 Multi-Caliber Lower Receiver Caliber: 6.5 Grendel (Type 2) Action: Semi-Automatic, Gas-Operated Twist Rate: 1:8 Precision Twist Handguard: 15" Lightweight M-LOK Free-Float Rail for accessories Upper Receiver: Forged 7075-T6 A3 AR Upper, hard-coat anodized Bolt Carrier Group: Full-Auto Profile Carrier, 9310 Steel Bolt (Nitride Treated & Staked)