Maxim Defense PDX Upper .300 AAC Blackout 5.5″ ARID

The Maxim Defense PDX complete upper is a compact, purpose-built assembly for .300 AAC Blackout platforms. It features a 5.5″ barrel and the Maxim HATEBRAKE muzzle booster to manage recoil and muzzle flash on short-barrel builds. The PDX upper is designed to install on any Mil‑Spec lower and uses a direct impingement operating system. Its short overall length makes it well suited for close-quarters or compact defensive configurations.

Key Specifications

• The caliber is .300 AAC Blackout for compatibility with .300 BLK ammunition.
• The barrel length is 5.5 inches for a compact profile.
• The overall length measures 14 inches as a complete upper assembly.
• The product type is a Complete Upper Receiver intended for installation on a lower.
• The model designation is PDX from Maxim Defense Industries.
• The finish is Matte for a subdued, non‑reflective surface.
• The color is Flat Dark Earth consistent with ARID styling.
• The operating system uses direct impingement as specified by the manufacturer.
• The muzzle device is a Maxim HATEBRAKE Muzzle Booster designed to reduce recoil impulse and muzzle flash on short barrels.
• This upper is designed for use with Mil‑Spec lower receivers for standard compatibility.

Compact and capable, the PDX upper packs short‑barrel performance into a durable, matte‑finished assembly. Its combination of a 5.5″ barrel, HATEBRAKE muzzle booster, and direct impingement design makes it a practical choice for users seeking a compact .300 AAC Blackout configuration that maintains controllability and standard lower compatibility.