Caliber: 5.56mm NATO/.223. Similar to Volunteer XV except has gas block with integral Picatinny-style rail, B5 SOPMOD stock, and upright B5 grip. Mid-length gas system, 15” aluminum S&W M-LOK forend. Primary Weapons Systems muzzle brake, and 5R rifling. Sights: WGS Tactical Folding Sight front and rear. XV Pro M-LOK 6mm ARC (No. 13518) has a 20” barrel. Overall Length: 37.5”-40.75”. Weight: 7.8 lbs. Introduced 2023. Model Pro M-Lok 13518.