Annex Defense Ultralight M-LOK ARCA Rail – Lightweight ARCA Interface for Hunting & Precision Rifles
The Annex Defense Ultralight M-LOK ARCA Rail allows you to convert any M-LOK handguard into a tripod- or bag-ready precision interface. Precision-machined from aerospace-grade 7075 aluminum and anodized for durability, these rails offer a balance of strength, weight savings, and performance that’s perfect for serious shooters and hunters.
Available in two sizes—Short (3.11") and XL (11.25")—and two finishes: Black and Tan.
Key Features
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Compatible with Standard ARCA-Swiss Tripod Clamps
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7075 Aluminum Construction – Aerospace-grade aluminum ensures maximum strength with minimum weight
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Hardcoat Anodized Finish – Black or tan finish resists wear, corrosion, and field abuse
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Low-Profile, Skeletonized Design – Cuts weight without sacrificing integrity
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Integrated Hard-Stop Shelf – Helps retain position under recoil or angled load
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Threaded Front-Stop Holes – Use included screws to prevent over-travel
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M-LOK Compatible – Securely mounts to any M-LOK handguard
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Made in the USA – Built with American materials by Annex Defense
Weight Specs:
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Short (3.11"): 36g (1.3 oz)
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XL (11.25"): 117g (4.12 oz)
What is R-Lock?
R-Lock is a tripod locking interface developed by Really Right Stuff. It adds precision-machined recoil lugs or indexing slots to an ARCA rail, helping to eliminate slip or forward creep under load or recoil.
While this Annex rail does not include R-Lock slots, it is fully compatible with R-Lock style tripod heads and can still clamp securely via friction just like any standard ARCA rail. If your tripod ball head supports R-Lock, you'll still benefit from added grip and security, even without indexed lugs.
Why We Recommend It
This is our preferred ARCA solution for the R-Lock footprint, especially when running tripods in hunting or precision field environments. Even without built-in R-Lock slots, the design works extremely well with modern tripod heads—and the weight savings and machining quality are top-tier.
We’ve run these rails across multiple fielded rifles and have found them extremely secure and well-finished. Annex Defense is a U.S.-based company, and we’re big fans of the product quality, especially for hunting-focused builds where ounces matter.
Installation Tips
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Scan the QR code on the product box for detailed install instructions and torque specs
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Install M-LOK nuts and screws loosely before placing on your handguard
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Tighten to spec after verifying clearance from gas blocks or barrels
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Use the included stop screws if you want to add a mechanical block to prevent forward movement during tripod work
