Maxim Defense(R) PDX-SD is a compact AR-platform semi-automatic pistol chambered in .300 Blackout. It features a 5.50 in barrel with an integrated suppressor system a black DLC-finished aluminum receiver with Picatinny top rail and an M-Slot handguard. This configuration uses a 20-round detachable magazine and is equipped with a black Maxim CQB brace and polymer grip.Key Features 5.50 in barrel chambered in .300 Blackout Integrated suppressor system for a compact suppressed configuration Semi-automatic operation with 20-round detachable magazine Black DLC-finished aluminum receiver with Picatinny top rail M-Slot handguard for compatible accessories Black Maxim CQB brace Black polymer gripMaxim Defense(R) builds compact firearms and components that emphasize portability modern ergonomics and accessory-ready layouts. The company is best known for its CQB brace and stock systems alongside AR-pattern platforms tuned for practical handling. Maxim Defense products are designed for shooters who want a compact setup that still supports optics lights and high-round-count range use.