Maxim Defense PDX 505-SPS 7.62x39mm 5.50in 20+1
Pros & cons
What works
- Folds to approx. 14.5 inches — 4.25 inches shorter than a fixed-brace AR pistol
- Proprietary SCW system reduces reciprocating mass for a 12% perceived recoil reduction vs. a standard buffer tube
- 5.10 lb weight is manageable for a 7.62x39mm platform, 1.8 lb lighter than a Galil ACE pistol
- Cold hammer-forged 5.50-inch barrel ensures durability with high-pressure steel-case ammo
Trade-offs
- Proprietary SCW system locks you into Maxim Defense for parts — a replacement buffer assembly costs $285
- Optic-ready means no sights included — adds minimum $200 for a capable red dot sight
- 7.62x39mm from a 5.50" barrel suffers severe velocity drop, losing ~40% energy vs. a 16" barrel
- Loud muzzle blast and significant flash — requires electronic hearing protection and a compensator or suppressor
Video review
Expert review
Specs at a glance
About this product
What is the Maxim Defense PDX 505-SPS 7.62x39mm? The Maxim Defense PDX 505-SPS is a compact, integrally-buffered AR-pattern pistol chambered in 7.62x39mm, designed around Maxim’s proprietary SCW (Short Compact Weapon) Pistol System that replaces a traditional stock or brace with a streamlined, folding rear section. This configuration results in an overall length of just 18.75 inches with a 5.50-inch barrel, creating a package that prioritizes concealment and maneuverability over long-range ballistics. It ships as an optic-ready platform with a 20+1 capacity, intended for shooters who require a highly compact, semi-automatic firearm that can be easily transported and deployed from confined spaces.
What is the Maxim Defense PDX used for?
The PDX 505-SPS is used for close-quarters defense and tactical applications where extreme compactness is mandatory before terminal ballistics. Its primary role is as a vehicle or pack gun, or for users operating in tight urban or indoor environments where its 18.75-inch folded length is a decisive advantage. The 7.62x39mm cartridge from a 5.50-inch barrel still delivers significant energy at short ranges, making it effective for defensive use inside 100 yards, though with pronounced velocity loss and louder muzzle blast compared to a full-length rifle like the Stevens 334 in .308 Win.
How does the Maxim Defense PDX compare to a CZ Scorpion EVO 3 S1?
The PDX 505-SPS offers superior ballistic performance in a slightly heavier and more expensive package than the popular 9mm CZ Scorpion EVO 3 S1 pistol. A PDX firing 7.62x39mm will deliver roughly 3-4 times the muzzle energy of 9mm from a comparable barrel length, making it a more lethal option for barrier penetration or against heavier threats. However, the CZ Scorpion is significantly cheaper, often under $900, and its 9mm ammunition costs about half as much, making it better for high-volume training. The PDX’s 5.10-pound unloaded weight is also 1.3 pounds heavier than a basic Scorpion, a tangible difference in a compact package.
What does it weigh and what are the dimensions?
The PDX 505-SPS weighs 5.10 pounds (81.6 oz) unloaded and measures 18.75 inches in overall length with the SCW system extended. Its most critical dimension is its folded length of approximately 14.5 inches, which is the true storage and transport measurement that defines its utility. The 5.50-inch cold hammer-forged barrel is the key component enabling this compactness, though it sacrifices roughly 600-800 feet per second of muzzle velocity compared to a 16-inch AK-pattern rifle firing the same ammunition, a trade-off for the reduced size.
Who is this NOT for?
This firearm is not for budget-conscious shooters, plinkers, or anyone seeking a traditional rifle experience. At $2,245.50, its cost prioritizes premium materials and a niche design over value, and the expensive, proprietary SCW system complicates aftermarket customization. It is also a poor choice for new owners unfamiliar with NFA regulations, as its short barrel and lack of a stock place it in a legal category often misconstrued as a “SBR”; understanding its status as a pistol is essential to avoid federal violations. For a straightforward, compliant introduction to centerfire rifles, a bolt-action like the Stevens 334 in .243 Win is a far simpler path.
What's in the box?
The PDX 505-SPS ships with the complete pistol, one 20-round C-Products Defense Duramag specifically engineered for 7.62x39mm in an AR platform, a rear single-point QD sling swivel mount integrated into the SCW system, and all necessary paperwork. Notably absent is any form of iron sights or an optic, as the platform is strictly “optic-ready” with a Mil-Spec picatinny rail; plan for an additional $200-$600 to mount a red dot. Maxim Defense does not include a case, sling, or cleaning kit, treating this as a core component purchase for knowledgeable users who will supply their own support gear.
Is the Maxim Defense PDX worth it at $2,245.50?
The PDX 505-SPS is worth its price only if your specific need justifies paying for the most compact, integrally-buffered 7.62x39mm AR platform on the market. You are paying a premium of roughly $1,000 over a standard AR pistol build for the refined SCW recoil system, premium barrel, and ultra-compact folded profile that few other manufacturers achieve. If your use case is general home defense or recreational shooting, a standard AR-15 or the aforementioned CZ Scorpion provides 90% of the utility for half the cost. This is a purpose-built tool for a specific, demanding scenario where its unique dimensions are non-negotiable.
Key attributes
| upc | 680017508012 |
| manufacturer | Maxim Defense Industries |
| manufacturer part number | MXM50801 |
| action | Semi-Auto |
| barrel length | 5.50" |
| caliber/gauge | 7.62 x 39mm |
| capacity | 20 + 1 |
| sights | Optic Ready |
Frequently asked questions
- Is it compatible with standard AR-15 parts?
- No, it is not fully compatible. While the fire control group and some pins are Mil-Spec AR-15, the proprietary Maxim Defense SCW buffer system, bolt carrier group, and upper receiver extension are unique and not interchangeable with standard AR parts. The 7.62x39mm bolt face and magazine well also require specific components like the included C-Products magazine.
- Does this work with a suppressor?
- Yes, the 5.50-inch barrel is threaded 5/8x24, which is the standard for .30 caliber muzzle devices, allowing direct attachment of many 7.62mm suppressors. However, firing supersonic 7.62x39mm from a barrel this short is exceptionally loud, often measuring over 165 decibels; a suppressor is highly recommended but will add 6-8 inches and 12-20 ounces to the front end.
- How long does shipping take to an FFL?
- For 'Online Only' items like this, standard processing is 3-5 business days before shipment. Transit time via common carriers like UPS or FedEx is typically 2-5 additional business days, depending on your location relative to our warehouse. Your designated FFL must have their license on file with us before we can release the shipment.
- Can I return it if I don't like it?
- No, all firearm sales are final once the transfer is completed at your Federal Firearms License (FFL) holder. We cannot accept returns on firearms due to federal regulations, except in the case of a verified manufacturer defect, which would be handled through Maxim Defense's warranty department directly. Inspect the firearm thoroughly at your FFL before completing Form 4473.