Calibers: .22 LR, 5.56 NATO, 5.7x28mm, 6mm ARC, 6.5 Grendel, .300 Blackout, .308 Win., 7.62x39mm, .350 Legend, 9mm Luger, .40 S&W, .45 ACP. The Mk4 is the carbine-length AR-15 direct-impingement platform. The Mk3 platform (AR-10) is based on the LR-308/DPMS Gen 1 high-pattern design. Pistol-caliber-carbine designations include MkG, MkGs, Mk9, Mk17, and Mk57. The Mk47 designation is for the 7.62x39mm chambering. Weight for the 5.56 MK4 is 6.4 lbs; length is 32.5” Add $150 for 5.7x28mm, 9mm; add $175 for Mk9 9mm with Colt-style SMG magazines. SEE POLITICAL PANIC PRICING.