HM Defense MonoBloc Upper — .223 Rem / 5.56×45mm NATO, 16" Black Cerakote Barrel, 7075-T6 Aluminum Receiver, 15" M-LOK Free-Float Handguard (16MBUP556 | 854164007005)
Build a battle-ready, accuracy-focused AR-15 with the HM Defense MonoBloc Upper (Model 16MBUP556 | UPC 854164007005). This complete upper assembly marries a precision 16-inch Black Cerakote barrel chambered for .223 Rem / 5.56×45mm NATO to a rugged 7075-T6 aluminum black-anodized receiver and a long 15-inch free-float M-LOK handguard — delivering the ideal balance of range, modularity, and durability for duty, hunting, competition, and serious range time.
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Product Overview
The HM Defense MonoBloc 16MBUP556 is a turnkey solution for builders and shooters who want a premium, no-compromise AR-15 upper. The 16" barrel delivers improved velocity and terminal performance over shorter barrels while remaining maneuverable in brush, vehicle, and urban environments. The 15" free-float M-LOK handguard provides ample real-estate for lights, lasers, grips, bipods and rail sections — all while removing contact from the barrel to maximize accuracy potential.
Manufactured to tight tolerances and finished with corrosion-resistant coatings, the MonoBloc upper offers the core ingredients shooters need for dependable function, repeatable accuracy, and years of service.
Key Features & Benefits
Chambered for .223 Rem / 5.56×45mm NATO — Reliable feeding with a wide selection of ammunition for training, duty, and hunting.
16" Black Cerakote Barrel — Precision machined and Cerakote finished for corrosion resistance and low glare; optimized for consistent groups and improved ballistic performance vs. short barrels.
7075-T6 Aluminum Black-Anodized Upper Receiver — Aircraft-grade material for superior strength-to-weight ratio and durability; anodized for finish longevity.
15" Free-Float M-LOK Handguard — Rigid, lightweight free-float design increases accuracy potential by isolating the barrel and provides abundant M-LOK slots for modular accessory mounting.
Continuous Top Picatinny Rail — Full-length rail for optics, backup sights, and repeatable mounting locations.
Monobloc Styling & Precision Fit — Machined for tight, reliable fitment to mil-spec lower receivers and consistent alignment of barrel, gas system, and rail.
Versatile Use Cases — Ideal for duty rifles, precision AR-15s, hunting setups, and multi-purpose range/competition builds.
Accessory Ready — Install optics, backup iron sights, lights, and foregrips without additional modification.
Specifications
Model: HM Defense MonoBloc Upper (16MBUP556)
UPC: 854164007005
Caliber: .223 Rem / 5.56×45mm NATO
Barrel Length: 16.00 inches
Barrel Finish: Black Cerakote (durable, low-glare)
Receiver Material: 7075-T6 Aluminum, Black Anodized
Handguard: 15.00" Free-Float M-LOK
Rail: Continuous Top Picatinny Rail
Platform Compatibility: Standard mil-spec AR-15 lower receivers
Intended Use: Duty, competition, hunting, precision range shooting
Intended Users: Law-enforcement, military, hunters, competition shooters, AR builders
Typical Applications
Duty & Patrol Rifles: Durable materials and long handguard mounting options make this upper ideal for lights, optics, and mission gear.
Precision & Match Builds: Free-float handguard and 16" barrel combine to reduce POI shift and improve repeatable groups.
Hunting & Varminters: Improved velocity and ballistic performance for field shots while maintaining maneuverability.
General Purpose Range Use: Balanced platform for training, drills, and optics zeroing.
Installation & Compatibility
The MonoBloc Upper is designed to mate with standard mil-spec AR-15 lower receivers. Basic armorer tools and knowledge are recommended for installation. Key tips:
Confirm lower receiver is mil-spec and legal in your jurisdiction.
Fit the upper to the lower, ensure proper alignment, and secure with takedown/pivot pins.
Verify gas block/gas tube contact and function; if the gas system requires tuning for specific ammo, consult a qualified armorer.
Torque and staking of fasteners should be performed per industry practice or by a qualified gunsmith.
If you are not comfortable performing installation or function checks, have a licensed gunsmith complete the build.
Performance & Handling
A 16" barrel in .223/5.56 offers a balanced mix of velocity and handling. Expect tighter groups and more consistent velocity compared to shorter barrels, making the 16MBUP556 well suited for precision engagements and medium-range targets. The free-float M-LOK handguard improves barrel harmonics and provides a comfortable gripping surface while allowing direct accessory placement without affecting accuracy.
Maintenance & Care
Bore & Chamber Care: Clean bore, chamber, and gas system after shooting sessions with proper solvent and brushes for .223/5.56.
Exterior Care: Wipe down Cerakote and anodized surfaces with a lightly oiled cloth to prevent corrosion.
Fastener Check: Periodically inspect handguard screws, gas block set screws, and rail hardware for secure torque.
Function Test: After installation and periodically thereafter, perform safe function checks to verify bolt carrier movement, gas system operation, and proper cycling.
Legal & Safety Notice
Always follow all firearm safety rules and local laws. This product is an upper receiver assembly intended for lawful use on compatible lower receivers. AR-15 configuration and certain features may be regulated depending on jurisdiction (e.g., state restrictions, NFA rules). Verify that your build complies with all applicable federal, state, and local laws before assembly or use. If uncertain, consult a licensed gunsmith or legal advisor.
Why Choose HM Defense MonoBloc 16MBUP556?
HM Defense combines durable materials, smart design, and rugged finishes to produce a workhorse upper that performs across missions. The 16-inch barrel gives you more effective range and velocity, while the 15-inch M-LOK free-float handguard creates a versatile, stable platform for accessories and optics. Whether you’re assembling a duty rifle, a precision AR, or a hunting carbine, the 16MBUP556 provides the critical elements to build around — strength, modularity, and repeatable accuracy.
SEO-Focused Summary
The HM Defense MonoBloc Upper 16MBUP556 (UPC 854164007005) is a complete AR-15 upper assembly featuring a 16" Black Cerakote barrel, 7075-T6 aluminum black-anodized receiver, and a 15" free-float M-LOK handguard. Chambered in .223 Rem / 5.56×45mm NATO, this upper delivers improved velocity and accuracy potential with robust accessory mounting for duty, hunting, competition, and tactical builds. Designed for mil-spec compatibility and long-term durability, the MonoBloc 16MBUP556 is a premium foundation for any serious AR-15 build.
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