The Maxim Defense PDX is a semi-automatic pistol chambered in .300 AAC Blackout, built around a compact platform for home defense and tactical use. 
 

Key Specifications 

• Model: Maxim Defense MXM-50822 
• Caliber: .300 AAC Blackout 
• Action: Semi-Automatic 
• Capacity: 20+1 rounds 
• Barrel Length: 5.5 inches 
• Weight: 5.6 lbs 
• Finish: Flat Dark Earth 
   

Detailed Features 

The PDX runs a direct gas impingement system, which keeps recoil manageable and cycling reliable. The upper and lower receivers are billet aluminum — strong but not heavy. The M4-style flat top upper accepts standard optic mounts. The lower has an integrated trigger guard, removing the sharp edges typical of bolt-on guards. 
 
The ALG Combat Trigger (ACT) has a clean pull, which helps with control during faster strings of fire. The M-Lok compatible free float forend keeps accessory mounting options open without adding unnecessary weight up front. The Maxim Defense HATEBRAKE muzzle booster reduces felt recoil and helps manage muzzle movement. 
 

Target Audience 

The PDX is aimed at shooters who need a compact, maneuverable package with .300 BLK capability. It fits home defense use, where short overall length matters in tight spaces, and serves tactical applications that require suppressor compatibility. 
 

Usage Scenarios 

The 5.5" barrel keeps the overall footprint small. Inside a structure, that matters. The .300 AAC Blackout cartridge covers a range of distances effectively and works with both supersonic and subsonic loads, which makes the platform useful for suppressed configurations.

Owners of the Maxim Defense PDX in .300 AAC Blackout tend to respond positively, with a few recurring concerns.

The compact size is consistently praised. Shooters who want something maneuverable for home defense find the PDX easier to handle in tight spaces than a full-length rifle. The adjustable brace and suppressor-ready design are also noted as standout features for users who plan to run a can.

Shooting feel gets good marks overall. Recoil with .300 BLK is mild, and the HATEBRAKE contributes to muzzle control. Both newer and more experienced shooters find the platform accessible.

Build quality is generally regarded well — the billet construction feels solid in hand. Price is a common topic though, with some buyers finding it high compared to other options in the space. Aftermarket support and available upgrades draw enthusiast interest, and most users find the platform customizable enough to suit their setup.