The Maxim Defense Industries SPS 505 PDX is a semi-automatic pistol chambered in 7.62x39mm. It pairs a 5.5-inch barrel with a 20+1 capacity, giving it more rounds and more barrel than most pistols in the tactical category — at the cost of a 5.10 lb loaded weight and an 18.75-inch overall length. 
 

Key Specifications 

• Caliber: 7.62 x 39mm 
• Barrel Length: 5.5 inches 
• Capacity: 20+1 rounds 
• Weight: 5.10 lbs 
• Overall Length (OAL): 18.75 inches 
• Type: Semi-Auto Handgun - Tactical 
• Finish Color: Flat Dark Earth 
• Frame Material: Aluminum 
• Stock Material: Synthetic 
• Sights: Optic Ready 
• Muzzle Device: Maxim Hate Brake 
   

Features 

The aluminum frame keeps weight reasonable given the caliber, and the anodized FDE finish holds up to field use. The optic-ready sights let you mount whatever glass suits your application — iron sights aren't included, so plan for an optic or aftermarket irons from the start. The Maxim Hate Brake muzzle device reduces recoil and muzzle rise, which matters when running 7.62x39 from a short pistol platform; follow-up shots are noticeably faster with it installed. 
 
The 20+1 capacity is one of the higher counts you'll find in this category. The compact 5.5-inch barrel makes it maneuverable in tight spaces while still extracting reasonable velocity from the 7.62x39 cartridge.

Buyers of the Maxim PDX in 7.62x39 FDE tend to focus on two things: the caliber choice and the size. The 7.62x39 cartridge gets a lot of attention because it's familiar to rifle shooters, and having that round in a pistol-size package is the main draw. People who already own AK-pattern rifles appreciate the ammunition commonality.

Build quality consistently gets positive marks. The aluminum construction feels solid, and most users report no reliability issues after break-in. Ergonomics are generally favorable — the grip and controls work well for most hand sizes, though a few mention that recoil is more noticeable than expected given the overall weight of the platform.

The FDE finish draws mixed reactions. Tactical-leaning buyers like it; others prefer black or would want more finish options. The optic-ready setup without included irons is noted as a practical gap — you need to budget for sights on top of the purchase price.

Price is a recurring discussion point. The PDX costs more than many competitors, and opinions split between those who consider the Maxim name and build quality worth the premium and those who think comparable performance is available cheaper. It's generally positioned as a purpose-built tool rather than a budget option.