The Maxim Defense PDX is a semi-automatic rifle chambered in 5.56x45mm NATO, built around a 5.5-inch barrel that keeps the overall package compact without giving up the NATO caliber. At 5.1 lbs it's light enough to handle quickly in tight spaces. 
 

Key Specifications 

• UPC: 680017478025 
• Caliber: 5.56X45MM NATO 
• Action: Semi Automatic 
• Capacity: 20 Rounds 
• Barrel Length: 5.5 inches 
• Weight: 5.1 lbs 
   

Features 

The 5.5-inch barrel is the defining characteristic here. It makes the PDX genuinely compact - shorter than most pistol-caliber carbines - while keeping the 5.56 NATO round in the mix. That's a deliberate trade-off: muzzle blast increases at this barrel length, so it's worth running suppressed or with hearing protection. 
 
At 5.1 lbs with a 20-round magazine, it handles fast. The short overall length is the main reason shooters pick this over a standard-length AR configuration. 
 

Usage 

The PDX fits naturally as a truck gun or home defense platform where space is a constraint. It also shows up in tactical training courses where the compact format is part of the drill. Competitive shooters use it in classes that emphasize close-quarters handling. The 5.56 caliber keeps terminal performance reasonable at the distances these guns are typically used.

Discussions about the Maxim Defense PDX tend to focus on whether the compact format justifies the price. Most owners think it does. The build quality consistently draws positive remarks - the materials feel substantial and the fit is tight, which matters at this price point.

The compact size is the main selling point and people mention it frequently. Home defense and vehicle carry come up as the typical use cases. Shooters who've run it in training note it handles recoil better than expected for the barrel length.

The price is the most common friction point. It costs more than standard-length AR builds, and some buyers debate whether the size advantage alone is worth the premium. Aftermarket support gets discussed too - the platform has options but not the sheer volume of parts you'd find for a mil-spec AR. The adjustable brace tends to get favorable mentions for how it fits different shooters.