Diamondback DB15 Obsidian .300 Blackout Pistol, OD Green
Pros & cons
What works
- Weighs 6.25 lbs (100 oz) unloaded—3 oz lighter than a comparable Smith & Wesson M&P15 Pistol in the same configuration.
- Includes a 30-round Magpul PMAG and SB Tactical SBA5 brace—a $130 value if purchased separately.
- Forged 7075-T6 aluminum receivers and mil-spec 8620 steel bolt carrier group—surpasses cast or 6061-T6 aluminum for long-term durability.
Trade-offs
- Obsidian muzzle brake is loud and concussive—unsuppressed fire produces 162 dB at the shooter's ear, 8 dB louder than a standard A2 flash hider.
- No adjustable gas block from factory—shooters switching between heavy subsonic and light supersonic loads may experience cycling issues without tuning.
- Pistol brace, while functional, provides less consistent cheek weld than a fixed rifle stock, affecting rapid sight acquisition for some shooters.
Video review
Expert review
Specs at a glance
About this product
The Diamondback DB15 Obsidian is an AR-style pistol chambered in .300 AAC Blackout, designed to provide compact power in a pistol-length platform while sidestepping NFA paperwork for a short-barreled rifle (SBR). This configuration ships in Olive Drab Green with an SB Tactical SBA5 pistol brace, a forged aluminum receiver set, and a 9-inch M-LOK handguard. It's a factory-built solution for shooters who want .300 Blackout terminal ballistics and suppressor compatibility without an immediate Form 1 tax stamp.
What is the Diamondback DB15 Obsidian used for?
The DB15 Obsidian is used for close-quarters defensive applications, truck or backpack carry, and as a quiet, high-energy suppressed platform when paired with a compatible can. Its .300 Blackout chambering delivers more energy than 5.56mm from a short barrel, making it ballistically effective from a 9-inch barrel, especially with 110-125 grain supersonic or 190-220 grain subsonic ammunition. Its overall length of 27.5 inches and 6.25-pound weight make it maneuverable indoors or in vehicles, but it lacks the stock-based shouldering stability of a true rifle like the Stevens 334 in .308 Win.
How does the Diamondback DB15 Obsidian compare to building a .300 Blackout pistol from parts?
The DB15 Obsidian is a better choice for new builders or those prioritizing a known, factory-backed warranty over the custom configuration potential of a parts kit. Assembling a .300 Blackout pistol piece-by-piece from quality components often costs $100-$300 more than this $1,025.99 factory gun, not counting the specialized tools and gauges needed for proper headspacing and barrel nut torque. Diamondback's build uses a mil-spec, shot-peened 8620 steel bolt carrier group and proper gas system tuning, which inexperienced builders frequently misconfigure, leading to under-gassing with subs or over-pressure with supers.
What does it weigh and what are the dimensions?
The pistol weighs 6.25 pounds (100 ounces) unloaded, with a 27.5-inch overall length from the end of the Obsidian muzzle brake to the back of the SBA5 brace. Its 9-inch handguard provides 7.5 inches of usable M-LOK real estate for mounting lights and handstops, while the brace extends 5 inches from the buffer tube and adjusts through six positions. While compact, it's 2.5 inches longer overall than some 5.56mm AR pistols with collapsible braces, due to the muzzle device and this specific brace model.
Who is this NOT for?
This pistol is not for shooters seeking a .300 Blackout rifle for 200+ yard target work or those legally restricted from owning AR-style pistols by state AWBs. The 9-inch barrel, while optimal for .300 Blackout powder burn, experiences a velocity drop of roughly 175-200 fps per inch of barrel loss compared to a 16-inch carbine, diminishing supersonic round effectiveness past 150 yards. It's also a poor choice for beginners whose first experience with firearms should be simpler manual-of-arms platforms, like the break-action Stevens 555 Sporting .410 shotgun.
What's in the box?
The factory box contains the complete DB15 Obsidian pistol, one 30-round Magpul PMAG, an Obsidian muzzle brake threaded 5/8x24, an SB Tactical SBA5 pistol brace, a standard carbine buffer and spring, and the obligatory chamber flag and manual. It ships with a fully assembled upper and lower, requiring no additional tools for initial function check. Note that some states restrict magazine capacity; Ironclad Armory complies with all applicable laws, but availability of the 30-round PMAG is jurisdiction-dependent.
Is the Diamondback DB15 Obsidian worth it at $1025.99?
At $1,025.99, it is worth the cost for a shooter wanting a turnkey, suppressor-ready .300 Blackout pistol from a known manufacturer with a functional warranty. This price is approximately $175 less than a comparable Smith & Wesson M&P15 Pistol in .300 Blackout, while offering a more aggressive muzzle brake and an M-LOK handguard versus standard Picatinny. The value lies in its out-of-the-box readiness for a suppressor, QD sling mounts, and a robust bolt carrier group—components that would add $250+ if upgraded separately on a budget pistol.
Key attributes
| upc | 810035756717 |
| manufacturer | Diamondback Firearms |
| manufacturer part number | DB1984B101 |
| action | Semi-Auto |
| barrel length | 10" |
| caliber/gauge | .300 AAC Blackout |
| capacity | 30 + 1 |
| color | Olive Drab Green |
| length | 7.5'' |
| magazine included | 1 x 30-Round |
| model | DB15 |
| number of magazines | 1 30 rd. PMag |
| product type | AR |
| safety | Selector Switch |
| shipping weight | 0.0 |
| sights | No Sights |
Frequently asked questions
- Is it compatible with standard AR-15 parts?
- Yes, the upper and lower receivers are mil-spec forged 7075 aluminum, compatible with most aftermarket AR-15 components. Note that the barrel is specifically chambered for .300 AAC Blackout and uses a pistol-length gas system, so swapping in a 5.56 NATO barrel requires also changing the bolt head and ensuring proper gas port alignment. Standard .30-cal suppressor mounts with a 5/8x24 thread pitch will fit directly.
- Does it ship with the brace attached?
- Yes, the SB Tactical SBA5 pistol brace is installed on the buffer tube from the factory in accordance with current ATF regulations. The brace is adjustable through six positions and can be removed with an armorer's wrench, though removal may affect the firearm's classification. Always verify state and federal laws regarding pistol braces before modification.
- How long does shipping take to an FFL?
- Ironclad Armory processes orders within 2-3 business days prior to shipping. Transit time to your chosen Federal Firearms License (FFL) holder depends on carrier and distance, typically 3-7 business days. You must contact your FFL dealer in advance to provide their license and coordinate pickup—we cannot ship directly to a home address.
- Can I use 5.56 NATO ammunition in this?
- No, firing 5.56 NATO or .223 Remington in a .300 Blackout chamber is extremely dangerous and can cause catastrophic failure. The .300 Blackout case head is the same diameter as 5.56, but the chamber dimensions are different. Always verify cartridge marking before loading; we recommend using distinctly different magazines (like .300 Blackout-specific PMAGs) to prevent mix-ups.
- Does this work with a suppressor?
- Yes, the 5/8x24 thread pitch on the Obsidian muzzle brake is standard for .30-caliber suppressors. The pistol-length gas system and adjustable buffer weight (a common upgrade) help manage increased backpressure when suppressed. For optimal function with subsonic ammunition, you may need to tune the gas block, which requires a 0.05-inch hex key and proper timing.