The Maxim Defense SPS 505 PDX is a semi-automatic pistol chambered in 5.56 NATO (also accepts .223 Rem) with a 5.5-inch barrel and 20+1 capacity. It weighs 5.9 lbs with an aluminum frame and gray finish. 
 

Key Specifications 

• Manufacturer: Maxim Defense Industries 
• Model: SPS 505 PDX 
• Type: Semi-Auto Handgun - Tactical 
• Caliber: 5.56 NATO (accepts .223 Rem) 
• Barrel Length: 5.5 inches 
• Overall Length: 18.75 inches 
• Capacity: 20+1 rounds 
• Weight: 5.9 lbs (2.67 kg) 
• Finish Color: Gray 
• Frame Material: Aluminum 
   

Features 

 
The HATEBRAKE muzzle booster reduces recoil and keeps the gas-operated action cycling reliably on the short 5.5-inch barrel. The full-length Picatinny top rail is flat-top and optics-ready out of the box. The M-Slot compatible handguard accepts standard accessories. 
 
The rear single-point QD sling mount is built in. The SCW sub-compact weapon system uses an Urban Grey polymer grip. Maxim rates this at 2 MOA accuracy. The 18.75-inch overall length and 5.56 NATO chambering give it useful range for a pistol-platform firearm.

The Maxim Defense PDX gets strong marks from owners who prioritize compact form with rifle-caliber performance.

Build quality is the most consistent praise — the aluminum construction and overall fit feel on par with the price tier. Reliability in firing sessions is generally reported as solid, and the adjustable brace is well-received for fit customization.

Price is the most common objection. The PDX sits at a premium compared to other 5.56 pistol platforms, and buyers debate whether the Maxim-specific features justify the cost differential. Weight at 5.9 lbs runs heavier than some expect for a compact pistol, though most owners adapt to it. Recoil management with the HATEBRAKE is considered adequate by experienced shooters; newer shooters occasionally mention that rapid-fire control takes practice.