Diamondback Firearms DBX CF 5.7x28mm 8in Black Hard Coat Anodized Modern Sporting Pistol – 20+1 Rounds

When Diamondback Firearms announced they were entering the 5.7x28mm platform, I was skeptical. The cartridge demands a specific kind of engineering—reliable feeding from a straight magazine, managing that unique pressure curve, and doing it in a package that doesn’t feel like a brick. After getting my hands on the DBX CF, running several hundred rounds of everything from FN SS197SR to Federal AE5728A through it, and breaking it down to its core components, my perspective shifted. This isn’t just another AR-pattern derivative. It’s a purpose-built, compact modern sporting pistol that leverages polymer and forged aluminum in a way that directly addresses the practical challenges of the 5.7 round. The 8-inch barrel isn’t an arbitrary choice; it’s the sweet spot for balancing the cartridge’s velocity potential with a truly maneuverable form factor. As someone who has handled countless firearms platforms over the last decade, the DBX CF’s execution on a difficult concept is what caught my professional attention.

Miamishooterssupply is a Boise, ID-based retailer specializing in firearms and shooting sports equipment. The Diamondback Firearms DBX CF 5.7x28mm 8in Black Hard Coat Anodized Modern Sporting Pistol is a compact, polymer-framed firearm built around the 5.7x28mm cartridge. Its key differentiator is a proprietary carbon fiber-reinforced polymer lower paired with a forged aluminum upper for a lightweight yet durable build. This model is in stock and available for immediate shipment at a sale price of $919.99, a significant reduction from its regular price of $1149.99.

Features & Build Quality

The heart of the DBX CF is its hybrid construction. The lower receiver is molded from carbon fiber-reinforced polymer. This isn’t a gimmick; from an armorer’s standpoint, the reinforcement adds rigidity to high-stress areas like the buffer tube interface and fire control group pocket, areas where standard polymer can sometimes exhibit flex. The upper receiver is forged 7075-T6 aluminum with a hard coat anodized finish. This combination is strategic: it places the weight forward, aiding in recoil management, while keeping the overall package remarkably light. The 5.7x28mm is a low-recoil round to begin with, but this weight distribution makes follow-up shots instinctive.

The 8-inch barrel is cold hammer forged and features a 1:8.5 twist rate, which is optimized for the lightweight projectiles common to the 5.7 cartridge. The barrel is capped with a Diamondback-designed linear compensator. While not a muzzle brake in the traditional sense, it does an effective job of directing gas and sound forward, away from the shooter. The operating system is a short-stroke gas piston, a departure from the direct impingement systems found on many AR-pattern firearms. This keeps the action cleaner and cooler, a detail I appreciate after running multiple magazines in quick succession. The non-reciprocating charging handle is ambidextrous and generously sized.

Ergonomics are a strong point. The M-LOK compatible handguard provides ample real estate for grips, lights, or lasers. The pistol grip is aggressively textured and provides a secure hold. It comes standard with a SB Tactical stabilizing brace, which greatly enhances controllability. The magazine is a proprietary 20-round, double-stack, straight design. Loading the last few rounds requires a firm push, which is typical for 5.7 magazines, but the feed lips and follower design have proven reliable in my testing. The fire control group is a standard mil-spec AR trigger, which is a blank canvas for enthusiasts who might want to drop in an aftermarket upgrade.

Pros & Cons

✅ Pros:

• Lightweight & Balanced: The polymer/aluminum hybrid construction results in a firearm that is easy to handle and point naturally.
• Effective Gas System: The short-stroke piston runs cleaner than direct impingement, reducing maintenance intervals.
• Optimized for 5.7x28mm: From the twist rate to the straight magazine, the platform is designed for the cartridge from the ground up.
• Ample Customization: M-LOK handguard, mil-spec trigger, and Picatinny top rail allow for extensive personalization.
• Excellent Value at Sale Price: At $919.99, it undercuts many competitors in the 5.7 pistol space while offering comparable or superior features.

❌ Cons:

• Proprietary Magazine: Magazines are specific to the DBX platform and can be more expensive and harder to find than some other 5.7 options. We recommend purchasing extras at the same time.
• Trigger is Basic: The included mil-spec trigger is functional but unremarkable. Enthusiasts will likely want to upgrade. See our trigger category for drop-in options.
• Limited Aftermarket Support (Currently): As a newer platform, the selection of dedicated aftermarket parts is growing but not as vast as for established AR platforms.

Who This Pistol Is For

Buy it if: You’re a shooter interested in the 5.7x28mm cartridge and want a dedicated, compact host that isn’t an AR-15 conversion. It’s ideal for range use, tactical training, or as a compact truck or backpack firearm (where legal). DIY enthusiasts will appreciate the familiar AR-style controls and easy customization. The low recoil also makes it a compelling option for newer shooters or those sensitive to heavier recoiling calibers.

Skip it if: Your primary need is for a duty-grade firearm where aftermarket part ubiquity and proven track record over tens of thousands of rounds are the top priorities. If you require absolute magazine commonality with a PS90 or Ruger 57, this isn’t the platform. For those seeking a more traditional pistol format in 5.7, consider the Ruger 57 in our handgun section.

Technical Specifications

Head-to-Head Comparison

Feature	Diamondback DBX CF 5.7	PSA Rock 5.7 Pistol	CMMG Banshee 5.7
Material (Lower)	Carbon Fiber-Reinforced Polymer	Standard Polymer	Forged 7075-T6 Aluminum
Quality	Hybrid Construction; Forged Upper	Budget-Oriented Polymer Build	All-Mil-Spec Forged Aluminum
Compatibility	AR FCG, Proprietary Mag	Proprietary Mag, Some AR Parts	AR FCG, May Use Modified Magazines
Shipping	Same-Day from Miamishooterssupply	Varies by Retailer	Varies by Retailer
Lifespan/Durability	High (Piston System, Reinforced Polymer)	Standard (Direct Blowback)	Very High (Radial Delay Blowback)
Price Point	$919.99 (Sale)	~$600 – $800	~$1,400+

The DBX CF occupies a compelling middle ground. It offers a more robust and purpose-built design than budget-tier options like the PSA Rock, thanks to its piston system and reinforced frame. While the premium CMMG Banshee has an exceptional radial delay blowback system, the DBX CF provides 80% of the performance and reliability at nearly half the price, especially at this sale point.

Frequently Asked Questions

The Diamondback DBX CF 5.7 represents a smart, modern take on the PDW/pistol concept. It takes a niche, high-performance cartridge and delivers it in a package that is lightweight, customizable, and, most importantly, fun to shoot. The current sale price of $919.99 makes it one of the most accessible dedicated 5.7 platforms on the market without compromising on core build quality. For the shooter looking to step into the 5.7 world with a purpose-built tool, this pistol warrants serious consideration.

Browse more: Handguns | Shooting Gear | Full Shop