Diamondback DB-15 Pistol .300 AAC Blackout 8″ SBA3
Pros & cons
What works
- 5.8 lb unloaded weight—over 2 lbs lighter than many 16-inch carbines, enhancing maneuverability.
- 8-inch barrel with 1:8 twist rate—ideal for stabilizing heavy subsonic .300 BLK rounds (190-220 grain) for suppressed use.
- Forged 7075 T-6 aluminum receiver—provides the same structural integrity as military-spec M4 lowers.
- Includes SBA3 brace and Magpul MOE grip—saves $120+ compared to purchasing these ergonomic upgrades separately.
Trade-offs
- No iron sights included—requires immediate additional investment of $80-$200 for a backup sight or optic system.
- Non-chrome-lined barrel—more susceptible to corrosion with certain propellants compared to a chrome-lined or nitride-treated alternative.
- Single 30-round PMAG—for a duty or training role, you'll need to purchase additional magazines immediately, adding $12-$15 each.
Video review
Expert review
Specs at a glance
About this product
The Diamondback DB-15 Pistol .300 AAC Blackout 8″ SBA3 is a compact, AR-pattern semi-automatic firearm configured and sold as a pistol under federal definitions, featuring a purpose-built 8-inch barrel chambered specifically for .300 AAC Blackout cartridges. It is designed around a forged 7075 T-6 aluminum receiver—the standard for durability—and integrates an SBA3 stabilizing brace and a 9-inch M-LOK handguard for immediate accessory mounting. This configuration delivers a short-barreled, highly modular platform that balances ballistic performance with a 26.5-inch overall length, making it a prime candidate for suppressor pairing and close-quarters use.
What is the Diamondback DB-15 Pistol used for?
This DB-15 Pistol is used for short-range tactical training, home defense, and as a suppressor host, where its .300 Blackout caliber shines brightest. The 8-inch barrel is optimized for subsonic ammunition when paired with a silencer, making it significantly quieter than supersonic 5.56 rounds from a similar barrel length. Its compact form factor and SBA3 brace make it maneuverable in confined spaces, while the M-LOK rail supports lights, lasers, and vertical grips for low-light or duty-oriented scenarios.
How does the Diamondback DB-15 Pistol compare to the Stevens 334 Rifle in .308 Win?
The Diamondback DB-15 Pistol is better for close-quarters, rapid engagement and suppressor use, while the Stevens 334 Rifle in .308 Win is superior for precise, longer-range shots. The DB-15's semi-auto action and 30+1 capacity allow for faster follow-up shots at distances under 200 yards, whereas the bolt-action Stevens 334 with its 20-inch barrel is built for deliberate accuracy and greater energy delivery at distances exceeding 400 yards. The DB-15 weighs approximately 5.8 pounds unloaded, making it roughly two pounds lighter and 14 inches shorter than the Stevens rifle, favoring mobility over raw power.
What does it weigh and what are the dimensions?
The DB-15 Pistol weighs 5.8 pounds (92.8 ounces) without a magazine or optics and measures 26.5 inches in overall length from the tip of the muzzle threads to the end of the fully extended SBA3 brace. Its 8-inch barrel contributes to the compact profile, while the 9-inch handguard provides ample real estate for accessory mounting without adding excessive forward weight. The collapsed length of the pistol with the brace folded is approximately 20 inches, facilitating storage in compact cases or vehicle compartments.
Who is this NOT for?
This firearm is not for beginners unfamiliar with NFA regulations concerning pistol braces and short-barreled rifles (SBRs), nor is it for shooters seeking a dedicated long-range precision platform. The .300 Blackout round from an 8-inch barrel experiences significant velocity and energy drop-off past 200 yards, making it ineffective compared to a rifle-caliber platform like the Stevens 334 in .243 Win. It is also a poor choice for budget-conscious shooters who do not plan to invest in a suppressor, as the cartridge’s primary advantage is realized with subsonic ammunition and a silencer.
What's in the box?
In the box, you receive one complete DB-15 Pistol with the SBA3 brace installed, one 30-round Magpul PMAG, and all necessary owner's documentation and compliance materials. Unlike some complete rifles, it does not include a chamber flag, sling, or cleaning kit, which are considered separate end-user acquisitions. The muzzle is protected by a standard thread protector, and the pistol is shipped in a cardboard box with foam inserts, not a hard-sided carrying case.
Is the Diamondback DB-15 Pistol worth it at $699.99?
At $699.99, this DB-15 Pistol is worth it for shooters who specifically need a suppressor-ready .300 Blackout host and understand they are paying for the configured platform, not just individual components. You are getting a complete, functional firearm with a reputable forged receiver, a quality Magpul grip and brace, and a barrel already threaded 5/8x24 for immediate device attachment, saving you approximately $150-200 in assembly labor and part-sourcing time compared to building from scratch. For a general-purpose AR in 5.56 NATO, this price point might buy more barrel length, but for this specific caliber and role, it represents solid value.
Key attributes
| upc | 810035756557 |
| manufacturer | Diamondback Firearms |
| manufacturer part number | DB191BB001 |
| atf type | Pistol |
| caliber/gauge | .300 AAC Blackout |
| capacity | 30 + 1 |
| number of magazines | 1 30rd. PMAG |
| package height | 3.6 |
| package width | 8.7 |
| barrel length | 8" |
| action | Semi-Auto |
| shipping weight | 6.95 |
| sights | No Sights |
| product type | Semi-Auto Pistol |
Frequently asked questions
- Is it compatible with standard AR-15 parts?
- Yes, the upper and lower receivers are mil-spec dimensions, ensuring compatibility with the vast majority of AR-15 triggers, bolts, charging handles, and safety selectors. The 5/8x24 muzzle threads are the standard for .30 caliber AR platforms, accepting nearly all .308 and .300 Blackout muzzle devices and suppressors from brands like SureFire and SilencerCo. The M-LOK handguard uses the ubiquitous attachment system for accessories from Magpul, SureFire, and Cloud Defensive.
- Does the SBA3 brace come installed?
- Yes, the SBA3 brace is installed from the factory and properly attached to the pistol's receiver extension buffer tube. The brace is in its fully functional, adjustable state, allowing for immediate shouldering and length-of-pull adjustment across its six-position settings. No further assembly is required beyond possibly installing your preferred optic or iron sights.
- What is the shipping time to an FFL?
- Standard shipping time from our warehouse to your selected Federal Firearms License (FFL) dealer is 3-5 business days after order processing and compliance verification are complete. All firearms must ship to a valid, verified FFL holder; we cannot ship directly to a private residence. You must contact your FFL in advance to confirm they accept transfers and provide their license to us.
- Can I use 5.56 NATO ammunition in this?
- Absolutely not. This pistol is chambered exclusively for .300 AAC Blackout. Attempting to chamber or fire a 5.56 NATO or .223 Remington round will result in a catastrophic failure, as the smaller projectile can travel down the .30 caliber barrel with disastrous results. Only use ammunition clearly marked .300 AAC Blackout or 7.62x35mm.
- Does this work with a standard .223/5.56 suppressor?
- No, it does not. While the 5/8x24 thread pattern may physically attach, the bore of a .223/5.56 suppressor is too small (typically .224 inches) for the .308-inch diameter projectile of the .300 Blackout. You must use a suppressor rated for .30 caliber or larger, such as a .308 or .46 caliber model, to avoid a baffle strike and severe damage.