Cross Machine Tool UHPR Mod 4 HDX Hybrid M-LOK AR-15 Handguard - 15"

Manufactured by Cross Machine Tool
Manufactured by Cross Machine Tool
1 Review

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The Cross Machine Tool Heavy Duty Xtreme Rails are built for the rigors of daily use. All HDX series rails include Nitride Hardened steel QD sockets to withstand daily sling carry. HDX Hybrid rails feature an incredible array of mounting space. A full-length Picatinny top rail provides space for forward mounted lights, NV/IR optics, or laser designators. M-LOK slots at the 3, 6, and 9 o'clock positions offer plenty of room for further expansion. Additional integrated short Picatinny rails can be found at the front of the rail.

  • M-LOK compatible
  • 6000 series extruded aluminum rail, MIL-SPEC Type III Class 2 hardcoat anodized
  • 7075 Aluminum barrel nut, Type III Class 2 hardcoat anodized
  • 17-4 PH cored stainless steel rail mounting attachment
  • Anti-rotation tabs time rail to upper receiver
  • Machine engraved T-marks
  • QD sling sockets
  • Includes barrel nut wrench
  • Compatible with most low-profile gas blocks
  • Inside diameter: 1.315”
  • Barrel nut diameter: 1.378"
  • Weight: 13 oz
  • Made in the U.S.A.

Cross Machine Tool Co., utilizing the latest machining technologies, offers high quality products that you’ll be excited to own.
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Accessory AttachmentM-LOK
BrandCross Machine Tool
FinishHardcoat Anodized
Gas System LengthExtended Rifle
Handguard Length15 in
Inner Diameter1.32 in
MaterialAluminum - 6000 Series
California Prop 65 warning

 WARNING: This product can expose you to chemicals, which are known to the State of California to cause Cancer and Reproductive Harm. For more information go to

Ratings & Reviews

1 review

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Awesome rail but qd mounts aren't anti-rotate

by -

It was between this and the Geissele mk13 and decided to go with this due to it being more price friendly and the great reviews. I gotta say, it's an awesome rail and I dont regret it. It's lightweight feels great in the hands, aesthetically pleasing, super easy to install and solid lock up. Doesn't have a torque spec on the screws so I just tightened them down as hard as I could with some blue loctite and it feels extremely solid. My only complaint is that the QD swivels are NOT anti rotate. They do rotate 360 degrees which I dont like because it causes your sling to twist. which is why I knocked off 1 star. I'll be using an aftermarket anti rotate qd sling mount.