Maxim Defense MXM50801 PDX 505-SPS 5.5" 21-Round Carbine

The Maxim Defense MXM50801 PDX 505-SPS 5.5" 21-Round Carbine represents a purpose-built platform for operators requiring compact, modular firepower in restricted-space environments. Developed for law enforcement tactical teams, civilian defensive shooters, and military personnel facing CQB or vehicle-mounted constraints, this carbine delivers rifle-caliber performance in a footprint that rivals full-size pistols. The 5.5-inch barrel and short overall length make it ideal for close-quarters work, breaching operations, and applications where maneuverability takes priority over long-range precision.

The PDX platform leverages a short-stroke piston operating system engineered for reliability across diverse ammunition loads and environmental conditions—a critical advantage in duty-critical scenarios where failures are not an option. The 21-round capacity magazine provides combat-effective magazine changes without excessive reload time, while the 5.5-inch barrel strikes the balance between velocity retention and flash signature management. Weighing 7.69 pounds, the system remains controllable under stress while maintaining the structural rigidity demanded of a gas-operated rifle, and its compact 22.1-inch overall length facilitates deployment from vehicles, tight hallways, and behind cover where conventional carbines become liabilities.

This carbine serves operators in law enforcement entry teams, private security professionals managing mobile or confined assets, and defensive shooters prioritizing concealability without sacrificing capability. The modular design accepts Picatinny rail accessories, allowing customization with optics, lights, and sound mitigation devices specific to your operational envelope. Compliance with applicable federal and state regulations is the buyer's responsibility; verification of local ordinances regarding short-barreled rifle registration or licensing is essential before purchase.