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MCX-SPEAR LT 16" UPPER AR CONVERSION KIT 5.56 NATO-BLACK
$1699.99
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SKU: UAMCX-556N-16B-LT-BLK
Overview
Built for shooters who want to modernize an M4/AR15-pattern rifle, this upper conversion kit is aimed at turning a standard lower into a folding firearm setup with a more adaptable operating system. It combines an adjustable gas system, gas piston design, ambidextrous charging handle, and quick-change barrel design to support a range of use cases, including suppressor setup and caliber or barrel-length changes. The included 16" 5.56 NATO upper assembly and 1913 rail stock adapter make it a practical option for users planning a configurable rifle build. It is a specialized upgrade, so buyers should be prepared for a more involved conversion than a simple parts swap.
Why Hunters Choose the Sig Sauer
Adapts Any
M4/AR15 spec lower assembly for
Includes Quick-change
Barrel design for easier caliber
Adjustable Gas
System supports suppressor optimization
Ambidextrous Charging
Gas deflector adds left- and
Receiver Extension
Delete stock adapter supports folding
Key Features
- Complete 16" 5.56 NATO upper assembly for MCX SPEAR LT conversion use.
- Adapts to any M4/AR15 spec lower assembly.
- Dual rod recoil assembly eliminates the buffer system.
- Adjustable gas system supports suppressor optimization.
- Quick-change barrel design allows caliber and barrel-length swaps.
- Ambidextrous charging handle includes a gas deflector.
- Includes a receiver extension delete stock adapter for 1913 rail stocks or braces.
Best Used For
- Hunters wanting a 16-inch 5.56 NATO upper for an M4/AR15 platform conversion
- Users planning a folding-stock setup with a compatible 1913 rail interface
- Shooters interested in an adjustable gas system for suppressor use
- Owners seeking a quick-change upper for swapping calibers and barrel lengths
- Serious users who want an ambidextrous charging handle and gas deflector
Specifications
| Accuracy Claim | Superior accuracy |
|---|---|
| Barrel Design | Nitride coated cold hammer forged barrel |
| Barrel Length | 16" |
| Buffer System | Eliminates buffer system |
| Cartridge | 5.56 NATO |
| Charging Handle | Ambidextrous charging handle with gas deflector |
| Color | Black |
| Compatibility | Any M4/AR15 spec lower assembly |
| Durability Claim | Superior durability |
| Flash Hider | Removable 3-prong flash-hider |
| Foldable Capability | Pic rail folding stock capabilities |
| Gas System | Adjustable gas system |
| Included Adapter | Receiver extension delete stock adapter |
| Operating System | Gas piston design |
| Platform | AR conversion kit |
| Quick Change Barrel Design | Yes |
| Recoil System | Dual rod recoil assembly |
| Reliability Claim | Superior reliability |
| Replaceable Parts | Cam Path Follower, Feed Ramp, Forward Assist/Deflector, Charging Handle Locking Pins |
| Round Count Claim | 20k rounds before any part replacements |
| Stockbrace Interface | Vertical 1913 rail system |
| Suppressor Compatibility | SLH & SLX suppressor systems |
| Upper Assembly Length | 16" |
Pros
- Adapts to any M4/AR15 spec lower assembly for broad platform compatibility.
- Includes a quick-change barrel design for easier caliber and barrel-length swaps.
- Adjustable gas system supports suppressor optimization.
- Ambidextrous charging handle with gas deflector adds left- and right-side usability.
- Receiver extension delete stock adapter supports folding or static 1913 rail stocks or braces.
- Complete 16-inch 5.56 NATO upper assembly includes a removable 3-prong flash hider.
Considerations & Trade-offs
- Requires an M4/AR15 spec lower assembly, so it is not a standalone firearm solution.
- The 16" 5.56 NATO configuration is fixed as listed here; caliber or barrel-length changes would depend on the quick-change barrel system and separate components.
- The included stock adapter is for 1913 rail system stocks or braces, so compatibility depends on the rear-end setup you plan to use.
- Suppressor-ready features are built in, but using that capability still depends on compatible SLH/SLX suppressor systems and related accessories.
Suggested Comparisons
- AR-15 upper receiver assemblies
- Folding stock adapter systems
- Suppressor-ready rifle components
- 5.56 NATO rifle barrels
Suggested Accessories
- AR upper receiver assembly
- 1913 rail stock or brace
- Suppressor-compatible flash hider
- AR cleaning kit
Frequently Asked Questions
What does this upper conversion kit fit?
It is described as adapting with any M4/AR15 spec lower assembly.
Does this kit include a complete upper?
Yes. The included items list a complete 16" 5.56 NATO upper assembly.
Can this setup be used with a folding stock or brace?
Yes. The description says it includes a receiver extension delete stock adapter so you may mount any folding or static stock or brace that uses a vertical 1913 rail system.
Is the gas system adjustable?
Yes. The product features an adjustable gas system for suppressor optimization.
What suppressor-related features are mentioned?
The description says it includes a removable 3-prong flash-hider ready to accept SLH and SLX suppressor systems, and it references an SLX/SLH next gen suppressor designed QD flash hider for Clutch-Lok adaptability. Specific suppressor compatibility details beyond that are not provided.