Geissele 08-244S Super Duty Upper Receiver with 9.3" M-LOK MK16 SMR: The Perfect CombinationGeissele Super Duty Stripped Upper is the perfect choice for those looking to build a custom AR rifle with top-quality craftsmanship. The upper receiver boasts Geissele's signature attention to detail, featuring a 9.3" MK16 Super Modular Rail that's seamlessly attached to the upper using a center-aligning tap, which eliminates the possibility of rail rotation during use. The barrel is constructed with a cold hammer forging process, ensuring maximum durability and performance. It is also chrome lined and coated in manganese phosphate, providing superior protection against wear and tear, and long service life for the rifle. Overall, Geissele's Super Duty Stripped Upper is a reliable and top-performing option for anyone looking to create a high-quality custom AR rifle. Features: Super Duty Upper9.3” MK16 Super Modular RailCold hammer forged, chrome lined, manganese phosphate coated barrelNOTE: All NFA regulations apply. Geissele Super Duty 5.56 NATO 10.3" 1:7" CHF Bbl DDC Stripped Upper Receiver w/9.3" M-LOK MK16 SMR 08-244S