CMMG DISSENT Mk4 Upper — 5.56x45mm NATO, 10.5" Barrel — Left-Side Charging — Armor Black — ZEROED™ Blast Comp — 9.60" M-LOK® Handguard — Picatinny End Plate — AR-15 Platform (Upper Only) — Model 55B8D86AB — UPC 810097509276
Build a compact, hard-running AR pistol or SBR with the CMMG DISSENT Mk4 10.5" 5.56x45mm Upper. Purpose-engineered for modern shooters, this upper combines a 10.50" 5.56 NATO barrel, left-side charging handle, and ZEROED™ Blast Comp with a lightweight 9.60" free-float M-LOK® handguard and Picatinny end plate. Finished in a durable Armor Black coating, the DISSENT Mk4 upper delivers premium ergonomics, accessory real estate, and reliable performance—ready for your favorite lower, optic, and BCG/charging handle solution.
Note: This listing is for the upper receiver group only. See the Included/Not Included section below.
Why Choose the CMMG DISSENT Mk4 10.5" Upper
Compact, duty-capable length: The 10.50" 5.56 NATO barrel balances portability with practical ballistics for defense, vehicle carry, and compact range builds.
Left-side charging handle: Stay on target and run the gun with your support hand—ideal for low-profile manipulations around barriers, prone, or from confined positions.
ZEROED™ Blast Comp: Directs blast forward to improve shooter comfort and reduce perceived concussion in tight spaces and team environments.
9.60" free-float M-LOK® handguard: Rigid, lightweight rail with ample M-LOK slots for white lights, hand stops, bipods, and pressure pads—without adding bulk.
Armor Black finish: Low-glare, wear-resistant coating that stands up to training cycles and tough field use.
Picatinny end plate: Rear rail section supports sling plates, accessories, and clean transitions between setups.
Key Specs (Quick Look)
Platform: AR-15 / CMMG DISSENT Mk4 upper
Caliber: 5.56x45mm NATO (compatible with .223 Rem)
Barrel Length: 10.50 inches
Muzzle Device: CMMG ZEROED™ Blast Comp (installed)
Handguard: 9.60" free-float M-LOK® aluminum
Charging: Left-side charging handle (support-hand friendly)
Receiver/Finish: Armor Black
Rear Interface: Picatinny end plate
Model / SKU: 55B8D86AB
UPC: 810097509276
Configuration: Upper receiver only (see Included/Not Included)
Designed for Real-World Performance
From the barricade to the bench, the DISSENT Mk4 upper emphasizes control, speed, and modularity. The left-side charger keeps your firing hand planted while you clear malfunctions or top off, and the free-float handguard preserves accuracy while giving you generous mounting slots for modern accessories. The ZEROED™ Blast Comp pushes concussion forward, making compact builds far more livable on indoor ranges, in vehicles, or during team drills.
Build Notes & Compatibility
Lower receivers: Pairs with most mil-spec AR-15 lowers. Confirm your buffer system/brace or stock (where legal) and local compliance.
BCG & charging handle: This product is sold as UPPER ONLY. Use a quality 5.56/.223 AR-15 BCG and a compatible charging handle or follow CMMG’s guidance for DISSENT-pattern configurations.
Gas system & tuning: For suppressed use, consider an adjustable gas block or tuned BCG to optimize reliability and recoil characteristics.
Optics & sights: Top rail accepts red dots, LPVOs, and backup sights; the 9.60" handguard supports offset optics and light placements.
Ideal Use Cases
Home & personal defense: Compact, maneuverable upper for close-to-mid-range engagements.
Vehicle/low-profile roles: Short overall length with a blast-managing comp for confined spaces.
Training & classes: Free-float M-LOK® rail supports mission-critical accessories and modern sling techniques.
Suppressed setups: Pair with a 5.56-rated suppressor and tuned gas for reduced signature (where legal).
What’s Included / Not Included
Included:
CMMG DISSENT Mk4 Upper, 10.50" 5.56 NATO barrel
ZEROED™ Blast Comp (installed)
9.60" Free-float M-LOK® handguard
Picatinny end plate
Left-side charging handle assembly (as equipped from factory)
Not Included:
Bolt Carrier Group (BCG)
Standard rear charging handle (not required for side-charge operation, depending on configuration)
Sights/optics, sling, lower receiver assembly, and magazines
Always confirm the exact contents of your package; configurations can vary.
Installation & Setup Tips
Verify safe/clear on your lower; separate upper and lower per AR procedures.
Pin the upper to your compatible AR-15 lower receiver.
Install your BCG and any required charging components per the DISSENT system guidance.
Torque & threadlocker: Follow manufacturer specs for muzzle devices, rail screws, and mounts.
Function check thoroughly, then zero your optic (common zeros: 36/50 yards for general use, 100 yards for precision).
Care & Maintenance
Keep the chamber, bore, and gas system clean; lube friction points per your BCG’s coating/manufacturer.
Re-check handguard and muzzle device torque after the first 100–200 rounds.
If running suppressed, adopt a more frequent cleaning cycle to manage carbon buildup.
Safety & Compliance
Use only quality 5.56 NATO / .223 Rem ammunition from reputable manufacturers.
Follow all federal, state, and local laws regarding barrel length, braces/stocks, NFA items, and suppressors.
Confirm headspace and component compatibility when installing your BCG.
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Compact. Controllable. Mission-ready. The CMMG DISSENT Mk4 10.5" 5.56 Upper in Armor Black pairs a left-side charger, ZEROED™ Blast Comp, and free-float M-LOK® rail to deliver a modern, maneuverable AR build you’ll trust on the range and beyond.
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