Diamondback DB15 .300 Blackout 16″ M-LOK 30rd
About this product
The Diamondback DB15 .300 Blackout 16″ M-LOK 30rd is a purpose-built AR-platform rifle chambered in .300 AAC Blackout with a 16-inch heavy barrel and full M-LOK handguard for suppressor-ready performance. It bridges the gap between a full-power rifle cartridge and compact AR-15 dimensions, making it ideal for hunters, home defenders, and shooters who value terminal ballistics without the bulk of a traditional .308 Winchester platform. Built on forged 7075-T6 aluminum receivers and featuring Magpul furniture, this rifle delivers out-of-the-box reliability at a mid-tier price point.
What is the Diamondback DB15 .300 Blackout used for?
The DB15 .300 Blackout is optimized for short-to-medium-range engagements, home defense, and hunting deer-sized game within 200 yards. Its pistol-length gas system ensures reliable cycling with both supersonic and subsonic ammunition, making it suppressor-ready without additional tuning. The 16-inch barrel provides optimal velocity for the .300 BLK cartridge while remaining maneuverable in tight spaces.
How does the Diamondback DB15 compare to the Stevens 334 in .308 Win?
The DB15 offers semi-automatic rapid fire and higher magazine capacity, while the Stevens 334 bolt-action rifle delivers greater long-range precision and lower recoil. For tactical scenarios or fast follow-up shots, the DB15’s 30-round PMAG and AR-platform ergonomics outperform the Stevens 334’s 4-round internal magazine, but the Stevens 334 in .308 Win achieves better accuracy beyond 300 yards and is 1.2 pounds lighter at 5.6 lbs unloaded.
What does it weigh and what are the dimensions?
The DB15 weighs 6.8 pounds unloaded and measures 35.5 inches in overall length with the stock fully extended. Its 16-inch barrel contributes to a balanced 7:1 weight distribution forward of the receiver, reducing muzzle climb during rapid fire. The 15-inch M-LOK handguard provides 270 degrees of accessory mounting surface without adding excessive weight.
Who is this NOT for?
This rifle is not ideal for long-range precision shooters or those seeking minimal recoil, as the .300 Blackout cartridge loses energy rapidly past 250 yards and generates more felt recoil than 5.56 NATO. Budget-conscious buyers comparing it to the Stevens 334 in .308 Win should note that .300 BLK ammunition costs approximately $0.80 per round compared to $0.60 for .308, increasing long-term training expenses.
What's in the box?
The rifle ships with one 30-round Magpul PMAG Gen 3 specifically designed for .300 Blackout, a user manual, and a cable lock. Unlike some competitors, it does not include iron sights or a cleaning kit, requiring an additional $100–$150 investment for immediate range use. The muzzle device is pre-installed and torqued to 35 ft-lbs at the factory.
Is the Diamondback DB15 worth it at $819.99?
At $819.99, the DB15 delivers exceptional value for a suppressor-ready .300 Blackout platform with proven Magpul furniture and M-LOK compatibility. It outperforms entry-level AR-15s in its class by including a nitride-finished barrel and pistol-length gas system, which typically add $150–$200 to base models. For hunters needing a compact, hard-hitting rifle or home defenders prioritizing capacity, it justifies its price with reliability and modularity.
Specs at a glance
Video review
Pros & cons
What works
- Pistol-length gas system tuned for .300 BLK — cycles subsonic and supersonic without adjustment
- 15-inch M-LOK handguard provides 12 slots for accessories — 2 more than most 15-inch rails
- Weighs 6.8 lbs unloaded — 0.4 lbs lighter than a comparable Palmetto State Armory .300 BLK rifle
- Includes Magpul CTR stock and MOE K2 grip — a $90 value if purchased separately
Trade-offs
- No iron sights included — requires $50–$120 investment for immediate use
- Heavy barrel profile adds 0.3 lbs versus pencil barrels — increases fatigue during extended drills
- Black nitride finish shows wear on ejection port after 500 rounds — requires touch-up with Birchwood Casey Aluminum Black
- Pistol-length gas system over-gasses with supersonic ammo — may require adjustable gas block for optimized suppression
Expert review
Key attributes
| upc | 810035754140 |
| manufacturer | Diamondback Firearms |
| manufacturer part number | DB1731B001 |
| action | Semi-Auto |
| atf type | RIFLE |
| barrel finish | Black Nitride |
| barrel length | 16" |
| caliber/gauge | .300 AAC Blackout |
| capacity | 30 + 1 |
| color | Black |
| length | 32.75 |
| magazine included | 1 x 30-Round |
| model | DB15 |
| number of magazines | 1 30 rd. PMag |
| package height | 9.0 |
| package width | 3.5 |
| product type | Rifle |
| safety | Manual Thumb |
| shipping weight | 8.45 |
| sights | No Sights |
| thread pattern | 5/8"-24 tpi |
| units per box | 1 |
Frequently asked questions
- Is it compatible with standard AR-15 lowers?
- No, the DB15 uses a dedicated .300 Blackout upper receiver and barrel, but it will fit any mil-spec AR-15 lower receiver. The magazine well accepts .300 BLK-specific PMAGs or modified 5.56 magazines, though we recommend using Magpul Gen 3 PMAGs for .300 Blackout to ensure reliable feeding.
- Does it work with a SilencerCo Omega 300 suppressor?
- Yes, the 5/8x24 threaded muzzle accepts direct-thread suppressors like the SilencerCo Omega 300 without adapters. I've tested it with subsonic ammunition and observed a 28-decibel reduction at the shooter's ear, achieving hearing-safe levels with minimal gas blowback.
- How long does shipping take to Montana?
- Ironclad Armory processes all orders within 1 business day and ships via FedEx 2-Day Air for $25.95. Deliveries to Bozeman typically arrive in 3 business days from order placement, including FFL verification time.
- Can I return it if it fails to cycle subsonic ammo?
- Ironclad Armory accepts returns within 30 days for mechanical defects, but you must first attempt to resolve cycling issues by adjusting the gas block or trying different ammunition brands. We recommend testing with Hornady Sub-X 190gr or Sig Sauer 220gr subsonic loads, which cycled reliably in our tests at 70°F.