Sig Sauer MCX MPX Stock Hinge Assembly 1913 Interface For Folding Stocks Steel Construction Black 8900807 UPC 798687660265
Product Description
The Sig Sauer MCX/MPX Stock Hinge Assembly (8900807) is a factory OEM high-strength folding stock hinge interface designed to mount folding stocks or brace extensions onto weapons equipped with rear MIL-STD-1913 Picatinny receiver rails. Purpose-built for the Sig Sauer MCX, MPX, and modern 1913 stock-compatible carbines, this hinge provides a rock-solid lockup in both deployed and folded positions.
Precision-machined from heavy-duty steel and finished in a corrosion-resistant black coating, the 8900807 hinge withstands violent recoil, hard tactical training, and field impacts without developing slop or play. Its heavy-duty spring-loaded detent mechanism allows operators to swiftly fold the stock for compact vehicle transport or concealed storage and deploy it instantly when going active.
Featuring a single cross-bolt clamp interface, the Sig Sauer Stock Hinge Assembly attaches directly to any rear vertical 1913 Picatinny section in seconds. Ideal for custom Sig builds, form 1 SBR projects, or replacing damaged stock mechanisms, this genuine factory assembly ensures defense-grade stability and lockup.
Armorer Bench Notes & Real-World Staging Guidance:
Fitment Matrix: Mounts to any firearm equipped with a rear vertical MIL-STD-1913 Picatinny rail section (including Sig MCX, MPX, custom AR 1913 endplates, and AK 1913 adapters). Accepts Sig Sauer folding stock struts and compatible aftermarket stock extensions.
- Perform a complete firearm safety check: drop the magazine, lock the bolt rearward, and visually inspect the chamber to verify zero live rounds are present.
- Clean the rear 1913 Picatinny rail section to remove oil, grit, or debris.
- Loosen the cross-bolt clamp on the hinge and slide the assembly onto the vertical 1913 Picatinny rail section at your desired height.
- Torque the mounting cross-bolt to 25–30 in-lbs using an inch-pound torque wrench to lock the hinge securely onto the rail.
- Attach your chosen stock strut or extension to the hinge knuckle using the appropriate factory hardware and threadlocker.
- Cycle the hinge multiple times between folded and deployed positions to verify smooth spring-loaded lockup.
Key Features
- Universal 1913 Picatinny Mounting: Clamps securely onto any vertical 1913 rail section for maximum modular stock versatility.
- Heavy-Duty Steel Construction: Precision-machined steel body eliminates flex and stands up to hard duty use.
- Positive Locking Mechanism: Spring-loaded detent design provides zero-play lockup in both folded and deployed positions.
- Corrosion-Resistant Black Finish: Protective coating guards against rust, weather exposure, and operational wear.
- Rapid Transport Folding: Folds flat along the receiver body for streamlined storage and concealed bag transport.
- Genuine Sig Sauer Factory OEM Part: Built to exact Sig defense-grade engineering standards for seamless function.
Product Specifications
- Brand: Sig Sauer
- Model/Series: Stock Hinge Assembly 1913 Interface
- MPN / SKU: 8900807
- UPC: 798687660265
- Platform Compatibility: Sig MCX, Sig MPX, and 1913 Picatinny Rear Receiver Rail Firearm Platforms
- Interface Type: Rear MIL-STD-1913 Picatinny Clamp
- Material: Heavy-Duty Steel
- Finish / Color: Matte Black
- Torque Spec (Rail Clamp): 25–30 in-lbs
- Weight: 4.8 oz
- Country of Origin: USA
