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Sig Sauer® MCX® / MPX™ Factory 6-Position Low-Profile Folding Stock Adapter – Mil-Spec Receiver Extension Tube Matrix – Vertical 1913 Interface – Aluminum Body – Coyote Brown – 8901458
Product Description
The Sig Sauer® MCX® / MPX™ Factory 6-Position Low-Profile Folding Stock Adapter (8901458) represents an absolute masterpiece in high-efficiency modular weapon logistics, stock stabilization configurations, and close-quarters structural adaptability. Expertly designed to elevate the cross-platform utility of Sig's signature short-stroke piston and pistol-caliber systems, this advanced interface component seamlessly integrates standard AR-15 ergonomics onto a specialized chassis. While legacy carbines suffer from fixed, elongated spatial constraints that compromise vehicular transit protocols or close-range maneuverability, this modular tracking upgrade allows operators to scale their weapon's physical envelope down into a hyper-compact storage layout. This premium Coyote Brown hardware asset (798681681310) establishes an indispensable foundation for custom rifle configurations, multi-mission tactical staging, and elite protective deployments.
The foundational core of this high-yield structural system relies on its precision CNC-machined aluminum architecture and heavy-duty locking hinge geometry. Bypassing loose multi-piece adaptations that invite severe mechanical play or alignment degradation over time, Sig Sauer engineered this unit with a rugged 1913 Picatinny rear clamp. This design locks flawlessly onto the vertical rail section of any standard MCX, MPX, or MCX Spear LT lower receiver to form an absolute zero-movement structural bridge. The adapter integrates a 6-position mil-spec sized carbine-style receiver extension tube, granting operators the precise mechanical authority to tune their length of pull (LOP) to accommodate thick body armor plates, heavy tactical chest rigs, or shifting environmental tracking boundaries.
The true operational triumph of this factory-original tactical upgrade lies in its sleek, or low-profile side-folding manual execution loop. With a firm upward or downward manual pressure toggle against the spring-loaded locking hinge, the stock cleanly folds flat along the left face of the upper receiver, minimizing outward spatial width. When swung out into the deployment track, the hardened steel hinge components lock together with an audible, tactile click, ensuring unyielding rigidity capable of handling intense administrative leverage and heavy weapon recoil profiles. Finished in a matching Coyote Brown / Coyote Tan protective armor coat to align perfectly with contemporary field camouflage and military issue furniture lines, this 1.18-pound structural asset yields total mechanical dominance over your rifle platform's rear infrastructure.
Includes: (1) Authentic Sig Sauer MCX/MPX 6-Position Low-Profile Folding Stock Adapter Assembly (Coyote Brown Aluminum Tube Body, Integrated Vertical 1913 Rail Cross-Clamp System, High-Tensile Internal Spring Locking Hinge), Packed in Original Branded Factory Sealed Retail Staging Packaging.
*Administrative Mounting, NFA Regulation & Workspace Guidance: The Sig Sauer 8901458 folding stock adapter features a 6-position mil-spec sized tube intended exclusively for true rifle buttstocks (such as Magpul SL-K, CTR, or B5 Systems stocks); WARNING: All National Firearms Act (NFA) rules and regional statutory regulations apply. Affixing a shoulder stock to a pistol configuration equipped with a barrel under 16 inches creates a Short-Barreled Rifle (SBR), requiring an approved BATFE Form 1 tax stamp prior to physical assembly. Conversely, this unit can be attached legally to existing registered NFA SBR lowers or factory rifle-length builds. When torquing the 1913 cross-bolt clamp to your receiver's vertical rear rail track, utilize a calibrated inch-pound wrench to avoid thread galling. Always explicitly verify that your host firearm is completely unloaded, cleared, and safe on your workbench before executing rear assembly upgrades.
Key Features
- Universal AR-15 Stock Integration: Outfitted with a standard mil-spec sized carbine extension tube, allowing you to mount your favorite aftermarket adjustable stock onto the MCX or MPX footprint.
- Sleek Low-Profile Folding Hinge: Built-in side-folding locking mechanical hinge collapses cleanly to significantly shorten your weapon's layout for tight vehicle storage or backpack transit.
- Rock-Solid 1913 Rail Connection: Integrates an overbuilt vertical Picatinny cross-clamp to generate an absolute, zero-play interface that blocks stock twisting or mechanical wobble.
- 6-Position Linear Adjustability: Features precision-machined positioning slots along the lower track to facilitate fast, highly granular length-of-pull settings for changing tactical gear.
- Premium Aerospace Aluminum Metallurgy: CNC-milled from top-grade structural aluminum billet to provide phenomenal shearing resistance without creating front-to-back balancing penalties.
- Camouflage Coyote Brown Coating: Treated with a low-reflective, weather-resistant Coyote Tan/Brown surface armor layer that resists chemical solvents and handles harsh trail scrapes.
Product Specifications
- Brand: Sig Sauer® (Engineered and quality-tested natively under elite factory specifications)
- Product Line: MCX® / MPX™ Tactical Modularity, Chassis Optimization, & Folding Stock Logistics
- Model Series Designation: 6-Position Low-Profile Folding Stock Adapter – Coyote Brown
- SKU / MPN: 8901458 (Alternative Industry Identifiers: 8901458-Sig / UT-8901458)
- Mounting Interface Footprint: Standard Vertical MIL-STD 1913 Picatinny Rail Section
- Receiver Tube Sizing Standard: Mil-Spec Dimensional Diameter (Accepts Standard AR Carbine Stocks)
- Adjustment Capacity Options: 6 Distinct Linear Mechanical Index Positions
- Hinge Structural Format: Side-Folding Manual Over-Center Mechanical Locking Knuckle
- Folding Orientation Vector: Collapses Flat to the Left-Hand Side of the Receiver Assembly
- Primary Body Metallurgy: High-Strength Precision CNC-Machined Aircraft Grade Aluminum Billet
- Hinge Core Pin Material: Hardened Severe-Duty Steel Alloy Cross-Axis Anchor
- Surface Finish Armor Protection: Non-Reflective Abrasion-Defeating Coyote Brown Coating
- Firearm Host Optimization: Sig Sauer MCX, MCX Spear LT, MCX Rattler, and MPX Platforms Natively
- Product Net Component Weight: ~1.18 lbs (~18.8 oz) - Robust Structural Reinforcement Mass
- Total Packaging Shipping Mass: ~1.50 lbs (Enclosed Inside Heavy Padded Protective Transit Boxing)
- UPC Barcode Number: 798681681310
