Diamondback DB Barrel — 5.56x45mm NATO, 5.50" Pistol-Length, Black Nitride, 4150 Chrome Moly Vanadium Steel | Model 556P55H50B8R (UPC: 815875019152)
Build a compact, hard-running AR-pattern pistol with the Diamondback DB 5.56x45mm NATO 5.50" Barrel. Machined from 4150 Chrome Moly Vanadium (CMV) steel and treated with a black nitride (QPQ) finish, this short, purpose-built barrel delivers impressive durability, easy maintenance, and reliable performance in a minimal footprint. A pistol-length gas system supports dependable cycling in compact configurations—ideal for CQB-style training, range fun, truck guns (where lawful), and suppressed builds tuned with the right components.
Why Choose This Diamondback 5.50" 5.56 Barrel?
Ultra-compact performance: At 5.50 inches, this barrel enables extremely short overall lengths for highly maneuverable AR-pattern pistols.
Duty-grade material: 4150 CMV steel brings superior heat tolerance and strength for sustained use compared to common 4140 alternatives.
Black Nitride (QPQ) inside & out: Increases surface hardness, fights corrosion, and reduces fouling buildup so the bore cleans faster and wears slower.
Pistol-length gas system: Designed for short systems to improve reliability with appropriate buffers, springs, and muzzle devices.
5.56 NATO chamber: Widely compatible with 5.56 NATO ammunition and (per typical 5.56 chamber guidance) .223 Rem loads—always verify with your manufacturer’s guidance and ensure proper headspace.
Key Features at a Glance
Caliber: 5.56x45mm NATO
Length: 5.50 inches
Material: 4150 Chrome Moly Vanadium (CMV) steel
Finish: Black Nitride (QPQ) for wear and corrosion resistance
Gas System: Pistol-length
Platform: AR-15 pattern pistols and SBRs (where lawful)
Model: 556P55H50B8R
UPC: 815875019152
Color: Matte black
Builder’s note: Confirm twist rate, muzzle thread, gas journal diameter, and profile on your specific production run to match gas blocks, suppressor mounts, comps/brakes, and bullet weights.
Performance Benefits You’ll Notice
Fast handling, small footprint: The short length keeps weight forward minimal, aiding quick target transitions in close quarters.
Easier cleanup: Nitride finish reduces copper/carbon adhesion for quicker bore maintenance after high-round-count sessions.
Heat & erosion resistance: 4150 CMV plus QPQ treatment helps mitigate throat erosion and supports consistent velocities over time.
Tunable reliability: Pair with an appropriate buffer system and an adjustable gas block (recommended, especially for suppressed use) to dial in smooth cycling.
Ideal Use Cases
Compact AR-pistol builds focused on maneuverability
Suppressed configurations tuned via adjustable gas and appropriate muzzle devices
Vehicle/truck firearms (where lawful) needing maximum portability
Range/cQB training where short OAL enhances movement and positioning
Build & Compatibility Checklist
Upper receiver: Mil-pattern AR-15 compatible with 5.56 NATO
Bolt carrier group: 5.56/.223 BCG, properly headspaced
Gas block/tube: Pistol-length tube; verify gas journal diameter (e.g., .750")
Handguard: Short free-float rail that clears/surrounds your muzzle device as needed
Muzzle device: Match the thread pitch; consider a device that aids backpressure management for short barrels
Buffer system: Heavier buffers and tuned springs can improve dwell and reliability on ultra-short builds
Installation Tips
Inspect, degrease, and lightly oil mating surfaces (extension, receiver, gas journal).
Torque barrel nut to spec and verify alignment for the gas tube.
Align and secure gas block (set-screw dimple or pin as appropriate); use thread locker per manufacturer direction.
Headspace check with GO/NO-GO gauges before live fire.
Function test & tune: Validate lock-back on empty mag; adjust gas/buffer if suppressed or if ejection pattern is erratic.
Specifications
(Twist rate, muzzle threads, gas journal, and exact contour may vary—confirm details to select the correct gas block, muzzle device, and ammo.)
Frequently Asked Questions
Q: Can I shoot .223 Remington through this barrel?
A: Most 5.56 NATO chambers accept .223 Rem. Always follow the manufacturer’s guidance and confirm proper headspace and ammunition selection.
Q: Do I need an adjustable gas block?
A: It’s strongly recommended for ultra-short barrels—especially on suppressed setups—to fine tune cyclic rate, reduce blowback, and optimize reliability.
Q: Is a 5.50" barrel accurate?
A: Yes—within its intended envelope. Barrel length primarily affects velocity; with quality ammo and a solid build, you’ll see excellent short-range precision.
Q: What about legal considerations?
A: Know your federal, state, and local laws regarding barrel length, overall length, pistol vs. SBR classification, and transport rules before building or modifying any firearm.
Recommended Pairings
Adjustable gas block + pistol-length gas tube
Heavier buffer/spring tuned for short barrels
Low-profile free-float handguard
Quality muzzle device (flash hider, brake, or suppressor interface)
Red-dot optic for CQB-oriented builds
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Shrink your build without sacrificing reliability. The Diamondback DB 5.56x45mm NATO 5.50" Black Nitride 4150 CMV Barrel gives you a tough, easy-to-clean, pistol-length foundation that’s tailor-made for compact AR-pattern projects—suppressed or unsuppressed—when tuned correctly.
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