Aero Precision 5.56 NATO AR15 ATLAS R-ONE Slick Side Complete Upper

No Forward Assist
Fully Assembled and Warrantied by Aero Precision
Ballistic Advantage Authorized DealerAero Precision Authorized Dealer

Aero Precision 5.56 NATO AR15 ATLAS R-ONE Slick Side Complete Upper

Available in 10.5″, 16″ Mid-Length, or 16″ Mid-Length Pencil Profile

This Slick Side Complete Upper is the quickest, most efficient, and lightweight way to assemble your custom firearm, fully assembled and warrantied by Aero Precision.  This AR15 Slick Side Complete Upper Receiver, paired with the ATLAS R-ONE handguard, streamlines the appearance of your AR15 by removing the Forward Assist. By combining our lightest handguards and barrel profiles with the No Forward Assist Upper Receiver, you can maximize the weight savings for your next build.

*NFA Rules apply for the 10.5″ barreled model.
**The muzzle devices are NOT pinned nor welded to the barrel.
***Does not include Bolt Carrier Group or Charging Handle.

AR15 Upper Receiver with No Forward Assist Features:

  • M4 Feed ramps
  • .250 takedown pin holes
  • Laser engraved T-marks
  • No forward assist provisions
  • Port door installed

ATLAS R-ONE MLOK Handguard Features:

  • Full top Picatinny rail for optional attachments
  • Quick disconnect sling socket at the 3, 6, and 9 o’clock positions
  • Compatible with low-profile gas blocks
  • 1.3″ Inside diameter
  • 1.5″ Outside diameter
  • Compatible with mil-spec AR15 upper receivers and barrels

5.56 Barrel Features: 

  • Select between a 10.5″ Carbine, 16″ Mid-Length or 16″ Mid-Length Pencil Profile
  • 5.56 NATO 1/7 twist, 4150 CrMoV, QPQ, gas port drilled
  • .750 gas block journal | .625 gas block journal (pencil profile)
  • Carbine length gas system (10.5″) | Mid-Length Gas (16″)
  • .0785 gas port
  • M4 Feed Ramp Extension
  • HP and MPI tested
  • Standard A2 flash hider

Choose between 3 Configurations:

APAR610602M2 – 10.5″ Carbine w/ 9″ ATLAS R-ONE MLOK
APAR610605M7 – 16″ Mid w/ 15″ ATLAS R-ONE MLOK
APAR610605M39 – 16″ Mid Pencil w/ 15″ ATLAS R-ONE MLOK

Also available with the ATLAS S-ONE Handguards


  • AR15 Assembled Slick Side Upper Receiver (No Forward Assist)
  • M-LOK ATLAS R-ONE Handguard
  • 5.56 NATO CMV Barrel
  • Low Profile Gas Block and Gas Tube
  • Product comes assembled
  • This complete upper does not include BCG or Charging Handle.
  • The muzzle brake with this complete upper receiver is NOT pinned nor welded to this barrel.

Product Information

Barrel Length

10.5", 16"

Gas System

Carbine, Mid-Length

Gas Block Diameter

.625, .750

Muzzle Thread



5.56 NATO

Attachment Type



Aero Precision

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