KAC Knights Armament URX 3.1 5.56 Free Float Rail Kit – 13.5″


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SKU: 30325 UPC: 819064010463

Product Description

The KAC URX 3.1 Rail is a free-floating, fully modular replacement forend for the AR-15 platform. Unlike traditional quad-rail designs, the URX 3.1 incorporates short sections of M1913 Picatinny rail at its front and rear ends for mounting tactical accessories, eliminating the commonly unused sections of rail for reduced overall weight and a more comfortable grip. A total of 4 integral QD sling swivel sockets are provided for ambidextrous sling compatibility.

Rifle Requirements: This URX 3.1 rail is compatible with any standard gas system length but does require the use of a low-profile gas block. Disassembly of the rifle’s gas system and removal of the factory barrel nut will be necessary. This forend uses a proprietary barrel nut that MUST be installed using a KAC URX Barrel Nut Wrench (PN: 20495, Sold Separately). For AR-15/SR-15 based platforms only; not compatible with SR-25 variants. Installation instructions, barrel nut, and hardware are included.


  • Weight: 13.8oz
  • Length: 13.5″
  • Free Float: Yes
  • Material: Aluminum
  • Finish: Black Anodizing




Technical Information


5.56 NATO / .223 Remington

Color / Pattern

Firearm Compatibility





Catalog Location

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 visit www.P65Warnings.ca.gov