The Diamondback DBX57 is a semi-automatic pistol chambered in 5.7x28mm with an AR-style platform. It runs a 20-round magazine (plus one in the chamber), has an 8-inch barrel, and comes in at 3 lbs. -- light for the capacity and caliber combination. The 7075-T6 aluminum receiver and black hard coat anodized finish give it durability without adding bulk. 
 

Key Specifications 

• UPC: 810035752696 
• Caliber: 5.7x28mm 
• Action: Semi-Automatic 
• Capacity: 20+1 rounds 
• Barrel Length: 8 inches 
• Weight: 3 lbs. 
• Finish: Black Hard Coat Anodized 
• Receiver Material: 7075-T6 Aluminum 
   

Detailed Features 

The AR-style platform puts familiar controls in familiar places, which helps shooters transition from an AR-15 without a steep learning curve. Magpul MOE K grips and M-LOK handguards handle the furniture. The M-LOK slots let you add lights, lasers, or other accessories without proprietary rail adapters. Barrel twist is 1:9", which stabilizes the 5.7x28mm round well at typical pistol ranges. The muzzle device also works to reduce felt recoil, which is already mild in this caliber. 
 

Usage Scenarios 

1. Home Defense: At 16 inches overall, it moves through interior spaces more easily than a rifle while still offering 20+1 capacity. 
2. Competitive Shooting: The low-recoil 5.7x28mm round and large capacity make it practical for speed-focused shooting events. 
3. Target Practice and Varmint Control: The caliber's flat trajectory and effective range suit outdoor target work.

The Diamondback DBX57 generally gets positive marks for its design concept, with a few real-world concerns worth knowing.

The M-LOK compatibility and lightweight AR-style platform come up most often in positive feedback. Fans of the 5.7x28mm caliber note its low recoil and high velocity, which makes rapid follow-up shots manageable and accurate at range. The 20+1 capacity for a pistol-format firearm is another recurring plus.

The criticisms center on ammunition. 5.7x28mm is less widely available than 9mm or .45 ACP, and it costs more per round -- both matter for regular practice. Some owners also report occasional feeding issues, which are noted more often with certain ammunition brands. Community discussions compare it directly to the FN Five-seveN and PS90 in the same caliber, where the Diamondback comes in at a lower price but with a less proven track record.

For buyers who already reload or have reliable 5.7x28mm sources, the DBX57 is a capable platform at a competitive price. For those who haven't priced out the ammunition, that should factor into the buying decision.