The Diamondback DB-15 is an AR-pattern pistol chambered in .300 AAC Blackout with an 8-inch barrel. It ships with an SB Tactical SBA3 pistol brace, M-LOK handguard, and Magpul grip in a black finish. The magazine capacity is 30 rounds. 
 

Key Specifications 

• Brand: Diamondback 
• Model: DB-15 
• Caliber: .300 AAC Blackout 
• Action: Semi Auto 
• Capacity: 30+1 
• Barrel Length: 8" 
• Color/Finish: Black 
   

Detailed Features 

• 8-inch barrel in an AR-pistol configuration; transfer as a pistol (no additional federal paperwork required at this barrel length under pistol classification) 
• M-LOK handguard for accessory attachment 
• SB Tactical SBA3 pistol brace included 
• Magpul grip 
• 30-round magazine included

Owners of the DB-15 in .300 AAC Blackout generally find it a solid compact AR-pistol, noting that Diamondback's fit and finish have improved noticeably on recent production runs. The 8-inch barrel gets most of the attention: short-range suppressor hosts report good results, and unsuppressed shooters accept the blast as the cost of the configuration.

Ergonomics draw mixed reactions. The SBA3 brace works well for most users and the M-LOK handguard gives enough real estate for a light or foregrip, but some find the Magpul grip angle less comfortable during extended range time. Trigger quality is the common point of contention, with many owners swapping it early.

For the price, most buyers consider the DB-15 a reasonable entry into .300 Blackout AR-pistol territory. Parts compatibility with standard AR-pattern components is a recurring plus, and the aftermarket support makes it easy to build out the platform over time.