The Maxim Defense PDX Upper Receiver is engineered to bring the performance and compact design of the full PDX platform to your existing AR-style lower. Designed for close-quarters applications, this upper features a 5.5-inch barrel and is available in 5.56 NATO, 7.62x39mm, or .300 Blackout. At the heart of the system is the integrated Maxim Hatebrake muzzle device, which reduces recoil, muzzle flash, and concussion for enhanced control and shooter comfort. The monolithic upper receiver is machined from aircraft-grade aluminum for strength and rigidity, while the free-floating handguard ensures accuracy and offers M-LOK slots for accessory attachment. This upper includes a full-length Picatinny top rail for optics and is compatible with Mil-Spec AR-15 lowers. Whether upgrading an existing platform or building a mission-specific PDW, the Maxim Defense PDX Upper delivers unmatched compact performance, reliability, and innovative design for tactical professionals and firearm enthusiasts alike.