SR-15 URX 3.1 Upper Receiver Group - Performance Enhanced

$1,975.00 - $2,185.00
When in stock, ships in 3 to 6 weeks, as we send our pin and weld out
Extremely Limited Production:
rail is discontinued, once sold out, no more will be available

SR15 M4 URX3.1 Upper Receiver Group - Custom

Unleashing Superior Firepower: SR15 URX3.1 Upper Receiver Group

While we here at Charlie's have an affinity for clone accuracy, we understand that improvements have been made to the M4 platform. We have asked Potomac Armory to build an upgraded upper for us with this idea in mind.  This is an extremely Limited Edition, so once we sell out, we are sold out.  Less than ten (10) have been allocated for sale in Fall, 2023.

Perfection in Construction

Enjoy a pinnacle of tactical design for a very popular upper receiver group.  Using premium firearm components from KAC, LaRue, Potomac and Surefire. Built with a LaRue Tactical 14.5" Rearden Steel barrel and Knights Armament URX 3.1 rail, this Mil-Spec upper receiver elevates the M4 platform to new heights. A precisely engineered mid-length gas system, utilizing a Mk12 gas block as salute to military grade components, and provides a smoother, softer recoil impulse for enhanced handling and comfort.

Premium Quality and Versatility

The unique upper receiver group doesn't just deliver on performance—it's also customizable to your needs. Choose from a selection of Surefire muzzle devices:  from 3-prong to 4-prong, Warcomp and closed tine, each pinned and welded to the barrel, getting to you a legal 16", and ensuring your upper receiver matches your personal specifications. Whether you're an enthusiast or a professional, this customizable aspect gives you the power to optimize your firearm.

Maximum Stability with Knight's Armament

The Knight's Armament URX 3.1 rail sits at the heart of this unit, providing a rock-solid handguard and mounting point. This military-grade component, alongside the phosphate bolt carrier group and milspec charging handle, provides a firm base for whatever challenges you face in the field.


  • Knight's Armament (KAC) 13.5" URX 3.1 Handguard Rail with Rail Panel Kit
  • LaRue Tactical 14.5" Stainless Mid-length Barrel, 1:7 twist chambered in 5.56 NATO, factory installed M4 extension with feedramps
  • Mil-Spec M4 forged upper receiver with hardcoat black Type III anodizing with M4 feedramps to marry-up with the barrel extension.
  • MK12 low profile gas block.
  • Mil-Spec Chrome-Lined Phosphated Bolt Carrier Group with 9310 steel MPI bolt and 8620 tool-grade steel carrier, and staked gas key.
  • Mil-Spec Charging Handle.
  • Surefire flash hider:  see drop-down menu for choices