Cross Machine Tool UHPR MOD 4 HDX Hybrid M-LOK AR-15 Handguard
Heavy-duty M-LOK rail with hardened steel QD sockets
Cross Machine Tool UHPR MOD 4 HDX Hybrid M-LOK AR-15 Handguard
The Cross Machine Tool UHPR MOD 4 HDX Hybrid M-LOK Handguard is built for hard use and daily sling carry, combining rigid construction with premium attachment points. Part of CMT’s HDX™ (Heavy Duty Xtreme) line, this rail features nitride-hardened steel QD socket inserts to resist wear over time—ideal for rifles that live on a sling and see regular training or duty use.
The rail’s hybrid design delivers a clean M-LOK setup with a robust mounting system that includes a 7075 aluminum barrel nut and a 17-4PH stainless mounting attachment. Anti-rotation tabs lock the rail to the upper receiver, and the design avoids side-loading the gas tube. With a 1.315″ inner diameter, it clears most low-profile gas blocks, and installation is simplified with no barrel nut shims required. Includes a barrel nut wrench for easy setup.
Features
- HDXâ„¢ design with nitride-hardened steel QD socket inserts (2 per side)
- 6000 series extruded aluminum rail with Type III Class 2 hard anodizing
- 7075 aluminum barrel nut with Type III Class 2 hard anodizing
- 17-4PH stainless rail mounting attachment (patent pending)
- Anti-rotation tabs time rail to upper receiver
- No barrel nut shims required
- Designed to avoid gas tube side load
- Machine-engraved T-marks that remain visible after paint
- Compatible with most low-profile gas blocks
- Includes barrel nut wrench
- Made and assembled in the USA
Specifications
- Inner Diameter: 1.315″
- Barrel Nut Diameter: 1.378″
- Overall Rail Dimensions: 1.96″ W x 2.195″ H
- QD Inserts: 4 total (2 each side), 4140PH nitride finished
- Finish: Mil-Spec Type III Class 2 hard anodized (rail and barrel nut)
- Material (Rail): 6000 series extruded aluminum
- Material (Barrel Nut): 7075 aluminum
- Material (Mount): 17-4PH cored stainless steel
- Mounting: M-LOK hybrid design with anti-rotation tabs
- Origin: Made & assembled in the USA
| Weight | N/A |
|---|---|
| Dimensions | N/A |
| Length | 12.5, 15 |
Compliance
NFA (National Firearms Act) compliance is crucial for legal ownership and transfer of regulated firearms and accessories like short-barreled rifles, suppressors, and certain types of ammunition, ensuring adherence to federal regulations to avoid legal penalties and ensure responsible firearm ownership.
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