The Diamondback Firearms DBX57 BGFB is a semi-automatic pistol chambered in 5.7x28mm with an 8-inch barrel. It has a hard coat anodized black finish, a Magpul MOE-K grip, and a side-folding pistol brace. The magazine capacity is 20 rounds. 
 

Key Specifications 

• Brand: Diamondback Firearms 
• Model: DBX57 BGFB 
• Caliber: 5.7x28mm 
• Action: Semi Auto 
• Barrel Length: 8 inches 
• Capacity: 20+1 
• Color/Finish: Black Hard Coat Anodized 
   

Detailed Features 

• 8-inch barrel with hard coat anodized black finish 
• Side-folding pistol brace 
• Magpul MOE-K grip 
• 20-round magazine capacity

Owners of the Diamondback DBX57 are drawn to the 5.7x28mm chambering in a compact, brace-equipped format. The side-folding brace is frequently called out as a practical feature that reduces the overall footprint for storage and transport. Most users find the Magpul MOE-K grip comfortable for extended range sessions.

Build quality opinions vary more than with some established brands. A number of owners report no issues out of the box, while others note tighter tolerances that require a break-in period before cycling becomes fully reliable with all magazine types. Fit and finish on the anodized receiver tends to get positive remarks.

The 5.7x28mm chambering is both the main draw and the main sticking point for buyers. Ammunition availability has improved but remains more limited and pricier than common handgun calibers, which is the most consistent complaint. Shooters who prioritize low recoil and high capacity find the trade-off worthwhile; those who want accessible ammo often hesitate.