The Geissele Super DutyA(R) Upper (Stripped) features the quality and workmanship you've come to expect from the Geissele name. The Super Duty upper receiver mates to a MK16 Super Modular rail via a center aligning tab, removing any chance of rail rotation. This family of rails is renowned by operators for their performance and comfort. It features an in-house Manganese Phosphate coated, CHF, Chrome Lined barrel with a 1-7 twist rate. Our barrels are precision machined and cold hammer forged at our state of the art facility in North Wales, PA; utilizing the highest quality materials available. The Super Duty Stripped Upper features a precisely balanced gas system, including the bomb-proofed Super Gas Block and fine-tuned gas port sizing, especially when combined with the Geissele Super 42 braided buffer spring (sold separately). These purposefully selected components minimize felt recoil while maintaining reliable cycling, even in adverse conditions. This stripped upper is ready to be furnished with your favorite components to ensure an accurate, reliable and smooth shooting experience.