Choose Options Quick view wishlist Compare ACI-15 16" Rifle Alpha 556 NATO or 300 Blackout $1,899.00 $1,799.00 - 4150 CMV Melonite - 1/7 Twist on both caliber options - M4 Feed Ramps - Mid-Length Gas System(556); Pistol Gas(300) - ACI Low Profile Gas Block - QPQ Corrosion Resistant Finish - SLR Rifleworks BCF Muzzle Device - 1/2-28(556) or... Choose Options Quick view wishlist Compare