Out of stock
SKU: MXM-508PP
UPC: 680017508166
MPN: MXM-50816
The Maxim SPS PDX Upper 5.56 5.5" is a compact upper receiver assembly engineered for operators who demand modularity, firepower, and rapid deployment in confined spaces. Built by Maxim Defense Industries—a manufacturer trusted across law enforcement and military platforms—this upper delivers 5.56 NATO capability in a short-barreled profile, making it ideal for close-quarters combat, vehicle operations, and dynamic breaching scenarios.
At just over one pound, it strikes the critical balance between weight savings and structural rigidity that separates field-proven gear from range-only solutions. This upper assembly integrates the SPS (Suppressible Piston System) platform, which decouples bolt carrier group movement from direct gas tube impingement—a proven reliability enhancement under suppressed or unsuppressed fire. The 5.5-inch barrel optimizes velocity for intermediate-range engagement while maintaining subsonic performance when paired with sound suppressors, critical for special operations and low-light tactical environments.
The PDX designation indicates purpose-built defensive indexing: the upper accepts standard AR-15 pattern lower receivers, allowing rapid reconfiguration across your existing platform ecosystem without tool changes or armorer-level intervention. Law enforcement tactical teams, military support units, and experienced civilian operators benefit most from this platform's modularity and suppression-ready design. Installation requires no permanent modifications, making it a versatile addition to any tactical setup.
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