Aero Precision 5.56 NATO M4E1 ATLAS R-ONE Complete Upper

Fully Assembled and Warrantied by Aero Precision
Ballistic Advantage Authorized DealerAero Precision Authorized Dealer

Aero Precision 5.56 NATO M4E1 ATLAS R-ONE Complete Upper

Available in 10.5″ Carbine or 16″ Mid-Length

Aero Precision 5.56 NATO M4E1 ATLAS R-ONE Complete Upper is the most efficient way to assemble your custom firearm, fully assembled and warrantied by Aero Precision. The R-ONE handguards are designed with size and weight in mind, providing the perfect addition to your lightweight build. Aero Precision’s proprietary ATLAS attachment system is a durable and dependable mounting platform, maintaining a slim profile while still providing the strength and stability customers have grown to love from Aero Precision handguards.

*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.

M4E1 Threaded Upper Receiver Features:

  • New enhanced forging that gives the upper receiver a “billet look.”
  • M4 Feed ramps
  • .250 takedown pin holes
  • Laser engraved T-marks
  • Includes port door and forward assist installed

ATLAS R-ONE 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 or 16″ Mid-Length barrel
  • 5.56 NATO 1/7 twist, 4150 CrMoV, QPQ, gas port drilled
  • .750 gas block journal
  • 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 2 Configurations:

APAR700702M2 – 10.5″ Carbine w/ 9″ ATLAS R-ONE MLOK
APAR700705M7 – 16″ Mid w/ 15″ ATLAS R-ONE MLOK


  • M4E1 Threaded Assembled Upper Receiver
  • M-LOK ATLAS R-ONE Handguard
  • 10.5″ or 16″ 5.56 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


Muzzle Thread



5.56 NATO

Attachment Type



Aero Precision

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