If you're looking to build an AR15 in 224 Grendel - this will get you well on your way. Barrel, Gas Tube, Adjustable Gas Block, Matched Bolt, Ejection Port Cover - $300 shipped .224 Baldwin Gun Works BGW (224 Grendel), 1:7 twist, 22”, 5/8x24 threaded muzzle, rifle length + 2” gas tube, .875"...