Upper Receiver (9 in Stock)





Product Description

The AR-15 is without question America’s Rifle. It has been our Nations chosen Service Weapon for over 60 years. It has defended our streets, our homes, and our homeland, but it was never intended to be a precision rifle.

Throughout the 1990’s Armorers from Special Operations Units came up with solutions to press it into service as a Recce or Sniper Support weapon. It garnered the affection of those who carried the modified carbines because of its lightweight, relative accuracy, and ammunition commonality. This would eventually grow into the storied MK12 program.

As the saying goes “there’s no free lunch”, and that is certainly the case with gas guns. From sloppy tolerances and poor-Quality Control to positional and thermal shift, for years gas gunners and armorers alike applied band aid fixes to eke out performance, never getting all the way there.

Here at Ridgeline Defense, we know this all too well. We have been a leader in Precision Rifle Training since our inception. Our staff has won or placed in the top five at every one of their eight appearances at the U.S. Army Sniper Competition and the USASOC Sniper Competition. On average we train over 500 Precision Rifle Shooters per year, spanning from Special Operators to novices. This level of end user experience coupled with the volume of students has allowed us to identify problems and develop solutions to solve the issues that plague gas gun shooters.

For shooters, by shooters, the RD15 Light Precision Rifle was born.

The RD15’s 7075 T6 Billet Aluminum upper receiver is elongated to provide more available mounting space for proper eye relief with a variety of optics and utilizes a semi-monolithic design where the handguard attaches to upper receiver itself and not the barrel nut, eliminating positional shift. It is finished in Type 3 Hard Coat Anodizing.

The handguard was specifically designed with ergonomics, mounting options, and wobble zone in mind. The handguard features full length RRS-Lock ARCA on the 6 o’clock with integrated MLOK slots. It also features MLOK on the 1,3,9, and 11 o’clock, with T-slot marked M1913 Picatinny running the entire length of the 12 o’clock. All of this while still maintaining an Outer Diameter (OD) of 1.58” wide and 2.0” tall, giving it the ergonomics of a fast-handling carbine. The full-length ARCA allows the gun to eliminate lateral wobble when shooting from barricades, bags, or supports, and it easily mounts to tripod, bipods and other ARCA accessories.

Our barrels are manufactured to our specifications by PROOF Research utilizing a 416R Stainless Steel Blank. They feature 1:7 Right Hand twist, chambered in .223 Wylde, and an intermediate-length gas system. They are thermally bedded into the upper receiver utilizing a proprietary installation process.

Our gas block features an indexing tab and dual-taper attachment method utilizing a jam-nut that threads on to the barrel itself, negating the use of set screws or pins drilled counter to the gas port.  This method allows us to hold very tight tolerances as the system becomes completely sealed, unlike a standard gas block that must be “pulled” down and into contact with the gas journal.  This ensures that when the system becomes pressurized during firing, and even more so with suppressor use, we have a consistent amount of gas shot after shot.  Furthermore, we utilize heat-treated 17-4 stainless steel with our stainless barrels to best match the thermal properties of the competing parts.

The RD15 Bolt is a Full-Auto Rated Mil Spec Carpenter 158 bolt that has been Magnetic Particle Inspected and High Pressure Treated. The carrier key is chrome lined, heat treated, gauged and properly staked in accordance with USGI specifications. The bolt and carrier are Diamond Like Coated for easy cleaning after prolonged suppressed fire. Every bolt is matched to its individual barrel during the Quality Control and Inspection process.

The RD15 LPR Upper Receiver is now available as a stand-alone product specifically at the request of our friends behind enemy lines in banned states.


  • 7075 T6 Billet
  • Semi-Monolithic Design
  • Type 3 Hardcoat Anodizing

  • 12 o’clock T-Slot engraved M1913 Picatinny
  • 1,3,9,11 o’clock MLOK
  • 6 o’clock Full Length RRS-Lock ARCA/MLOK

  • PROOF Research 416 Stainless Blank
  • Cut Rifling featuring 1:7 Twist
  • .223 Wylde Chamber
  • Ridgeline SDM Profile
  • 16” Intermediate Gas Available now


  • Weight: 101 oz
  • Width: 5 in
  • Depth: 30 in
  • Height: 5 in

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